regents chemistry
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REGENTS CHEMISTRY
(c) 2006, Mark Rosengarten
Setup of the Chemistry Regents Exam
What to bring to the exam
How to prepare for the exam
Things to keep in mind for the exam
Setup of the Exam
(c) 2006, Mark Rosengarten
85 total points: Part A (25-30 questions): Multiple-Choice questions that
test knowledge of basic concepts of chemistry Part B-1 (15-20 questions): Multiple-Choice questions the
test understanding and application of more advanced concepts, math and lab activities.
Part B-2: Short-answer and fill-in problem-solving type questions. Sometimes involving simple graphs or diagrams that must be labeled or filled in.
Part C: Short-answer and problem-solving questions involving show-your-work math problems, reading passages and practical applications of chemical principles.
What to Bring to the Exam
(c) 2006, Mark Rosengarten
Pen, blue or black ink Calculator (memories will be cleared, so back
them up) Your brain. Please don’t leave it at home.
WHAT NOT TO BRING: PDA’s and cell phones…these cannot be used as
calculators during the exam and use of one will result in removal of the exam paper. Cell phones must be turned OFF and be left somewhere other than where you are sitting.
A negative attitude. Just do the best you can!
How To Prepare
(c) 2006, Mark Rosengarten
DO NOT CRAM. Get your studying done with by the night before. Get a good night’s sleep and have breakfast the morning of the exam.
Use a review book with old exams, answers and explanations in it. Take the old tests and grade yourself. The questions you don’t understand why you got wrong make sure to see your teacher about.
Actively participate in any and all review classes and activities offered by your teacher.
Study vocabulary. Identify key words and use flash cards to help you remember what the meaning of those words are and the concepts behind them.
KEEP IN MIND!!!
(c) 2006, Mark Rosengarten
Handwriting must be readable. Must use pen except for graphs which you must use pencil
ALL work must be shown for math problems in parts B2 and C.
Include all units in your work and answers. Make sure to round off answers properly. Check your answers to make sure they make
sense with no contradictions. Read the question and answers twice to make
sure you understand. Make sure to do ALL parts of multi-part questions on parts B2 and C.
Use the Reference Tables as often as possible.
Mark Rosengarten’s Amazing Chemistry Powerpoint Presentation!
(c) 2006, Mark Rosengarten
Aligned to the New York State Standards and Core Curriculum for “The Physical Setting-Chemistry”
Can be used in any high-school chemistry class!
Please give the link to this file to your chemistry students! www.markrosengarten.com
Enjoy it!!! A LOT of work has gone into bringing you this work, so please credit me when you use it!
Outline for Review
(c) 2006, Mark Rosengarten
1) The Atom (Nuclear, Electron Config)2) Matter (Phases, Types, Changes)3) Bonding (Periodic Table, Ionic, Covalent)4) Compounds (Formulas, Reactions, IMAF’s)
5) Math of Chemistry (Formula Mass, Gas Laws, Neutralization, etc.)
6) Kinetics and Thermodynamics (PE Diagrams, etc.)7) Acids and Bases (pH, formulas, indicators, etc.)8) Oxidation and Reduction (Half Reactions, Cells,
etc.)9) Organic Chemistry (Hydrocarbons, Families,
Reactions)
The Atom
(c) 2006, Mark Rosengarten
1) Nucleons – click here for website on nucleons2) Isotopes – click here for website on isotopes3) Natural Radioactivity 4) Half-Life5) Nuclear Power6) Electron Configuration7) Development of the Atomic Model
Nucleons
(c) 2006, Mark Rosengarten
Protons: +1 each, determines identity of element, mass of 1 amu, determined using atomic number, nuclear charge
Neutrons: no charge, determines identity of isotope of an element, 1 amu, determined using mass number - atomic number (amu = atomic mass unit)
3216S and 33
16S are both isotopes of S S-32 has 16 protons and 16 neutrons S-33 has 16 protons and 17 neutrons All atoms of S have a nuclear charge of +16 due
to the 16 protons.website
Isotopes
(c) 2006, Mark Rosengarten
Atoms of the same element MUST contain the same number of protons.
Atoms of the same element can vary in their numbers of neutrons, therefore many different atomic masses can exist for any one element. These are called isotopes.
The atomic mass on the Periodic Table is the weight-average atomic mass, taking into account the different isotope masses and their relative abundance.
Rounding off the atomic mass on the Periodic Table will tell you what the most common isotope of that element is.
Weight-Average Atomic Mass
(c) 2006, Mark Rosengarten
WAM = ((% A of A/100) X Mass of A) + ((% A of B/100) X Mass of B) + …
What is the WAM of an element if its isotope masses and abundances are: X-200: Mass = 200.0 amu, % abundance = 20.0
% X-204: Mass = 204.0 amu, % abundance =
80.0%
amu = atomic mass unit (1.66 × 10-27 kilograms/amu)
website
Most Common Isotope
(c) 2006, Mark Rosengarten
The weight-average atomic mass of Zinc is 65.39 amu. What is the most common isotope of Zinc? Zn-65!
What are the most common isotopes of: Co Ag S Pb
FACT: one atomic mass unit (1.66 × 10-27 kilograms) is defined as 1/12 of the mass of an atom of C-12.
This method doesn’t always work, but it usually does. Use it for the Regents exam.
Natural Radioactivity
(c) 2006, Mark Rosengarten
Alpha Decay Beta Decay Positron Decay Gamma Decay Charges of Decay Particles
Natural decay starts with a parent nuclide that ejects a decay particle to form a daughter nuclide which is more stable than the parent nuclide was.
website
Alpha Decay
(c) 2006, Mark Rosengarten
The nucleus ejects two protons and two neutrons. The atomic mass decreases by 4, the atomic number decreases by 2.
23892U
Beta Decay
(c) 2006, Mark Rosengarten
A neutron decays into a proton and an electron. The electron is ejected from the nucleus as a beta particle. The atomic mass remains the same, but the atomic number increases by 1.
146C
Positron Decay
(c) 2006, Mark Rosengarten
A proton is converted into a neutron and a positron. The positron is ejected by the nucleus. The mass remains the same, but the atomic number decreases by 1.
5326Fe
Gamma Decay
(c) 2006, Mark Rosengarten
The nucleus has energy levels just like electrons, but the involve a lot more energy. When the nucleus becomes more stable, a gamma ray may be released. This is a photon of high-energy light, and has no mass or charge. The atomic mass and number do not change with gamma. Gamma may occur by itself, or in conjunction with any other decay type.
Charges of Decay Particles
(c) 2006, Mark Rosengarten
Half-Life
(c) 2006, Mark Rosengarten
Half life is the time it takes for half of the nuclei in a radioactive sample to undergo decay.
Problem Types: Going forwards in time Going backwards in time Radioactive Dating
website
Going Forwards in Time
(c) 2006, Mark Rosengarten
How many grams of a 10.0 gram sample of I-131 (half-life of 8 days) will remain in 24 days?
#HL = t/T = 24/8 = 3 Cut 10.0g in half 3 times: 5.00, 2.50, 1.25g
Going Backwards in Time
(c) 2006, Mark Rosengarten
How many grams of a 10.0 gram sample of I-131 (half-life of 8 days) would there have been 24 days ago?
#HL = t/T = 24/8 = 3 Double 10.0g 3 times: 20.0, 40.0, 80.0 g
Radioactive Dating
(c) 2006, Mark Rosengarten
A sample of an ancient scroll contains 50% of the original steady-state concentration of C-14. How old is the scroll?
50% = 1 HL 1 HL X 5730 y/HL = 5730y
Nuclear Power
(c) 2006, Mark Rosengarten
Artificial Transmutation Particle Accelerators Nuclear Fission Nuclear Fusion
Artificial Transmutation
(c) 2006, Mark Rosengarten
4020Ca + _____ -----> 40
19K + 11H
9642Mo + 2
1H -----> 10n + _____
Nuclide + Bullet --> New Element + Fragment(s) The masses and atomic numbers must add
up to be the same on both sides of the arrow.
Website
Particle Accelerators
(c) 2006, Mark Rosengarten
Devices that use electromagnetic fields to accelerate particle “bullets” towards target nuclei to make artificial transmutation possible!
Most of the elements from 93 on up (the “transuranium” elements) were created using particle accelerators.
Particles with no charge cannot be accelerated by the charged fields.
website
Nuclear Fission
(c) 2006, Mark Rosengarten
23592U + 1
0n 9236Kr + 141
56Ba + 3 10n + energy
The three neutrons given off can be reabsorbed by other U-235 nuclei to continue fission as a chain reaction
A tiny bit of mass is lost (mass defect) and converted into a huge amount of energy.
website
Chain Reaction
(c) 2006, Mark Rosengarten
Nuclear Fusion
(c) 2006, Mark Rosengarten
21H + 2
1H 42He + energy
Two small, positively-charged nuclei smash together at high temperatures and pressures to form one larger nucleus.
A small bit of mass is destroyed and converted into a huge amount of energy, more than even fission.
website
Electron Configuration
(c) 2006, Mark Rosengarten
Basic Configuration Valence Electrons Electron-Dot (Lewis Dot) Diagrams Excited vs. Ground State What is Light?
Basic Configuration
(c) 2006, Mark Rosengarten
The number of electrons is determined from the atomic number.
Look up the basic configuration below the atomic number on the periodic table. (PEL: principal energy level = shell)
He: 2 (2 e- in the 1st PEL) Na: 2-8-1 (2 e- in the 1st PEL, 8 in the 2nd and 1
in the 3rd) Br: 2-8-18-7 (2 e- in the 1st PEL, 8 in the 2nd, 18
in the 3rd and 7 in the 4th)
Valence Electrons
(c) 2006, Mark Rosengarten
The valence electrons are responsible for all chemical bonding.
The valence electrons are the electrons in the outermost PEL (shell).
He: 2 (2 valence electrons) Na: 2-8-1 (1 valence electron) Br: 2-8-18-7 (7 valence electrons)
The maximum number of valence electrons an atom can have is EIGHT, called a STABLE OCTET.
Electron-Dot Diagrams
(c) 2006, Mark Rosengarten
The number of dots equals the number of valence electrons.
The number of unpaired valence electrons in a nonmetal tells you how many covalent bonds that atom can form with other nonmetals or how many electrons it wants to gain from metals to form an ion.
The number of valence electrons in a metal tells you how many electrons the metal will lose to nonmetals to form an ion. Caution: May not work with transition metals.
EXAMPLE DOT DIAGRAMSClick here for website on
valence electrons and electron dot diagrams
Example Dot Diagrams
(c) 2006, Mark Rosengarten
Carbon can also have this dot diagram, which ithas when it forms organic compounds.
Excited vs. Ground State
(c) 2006, Mark Rosengarten
Configurations on the Periodic Table are ground state configurations.
If electrons are given energy, they rise to higher energy levels (excited state).
If the total number of electrons matches in the configuration, but the configuration doesn’t match, the atom is in the excited state.
Na (ground, on table): 2-8-1 Example of excited states: 2-7-2, 2-8-0-1, 2-6-3
website
What Is Light?
(c) 2006, Mark Rosengarten
Light is formed when electrons drop from the excited state to the ground state.
The lines on a bright-line spectrum come from specific energy level drops and are unique to each element.
EXAMPLE SPECTRUM
EXAMPLE SPECTRUM
(c) 2006, Mark Rosengarten
This is the bright-line spectrum of hydrogen. The topnumbers represent the PEL (shell) change that produces the light with that color and the bottom number is thewavelength of the light (in nanometers, or 10-9 m).
No other element has the same bright-line spectrum ashydrogen, so these spectra can be used to identifyelements or mixtures of elements.
website
Development of the Atomic Model
(c) 2006, Mark Rosengarten
Thompson Model Rutherford Gold Foil Experiment and Model Bohr Model Quantum-Mechanical Model
Thompson Model
(c) 2006, Mark Rosengarten
The atom is a positively charged diffuse mass with negatively charged electrons stuck in it.
website
Rutherford Model
(c) 2006, Mark Rosengarten
The atom is made of a small, dense, positively charged nucleus with electrons at a distance, the vast majority of the volume of the atom is empty space.
Alpha particles shotat a thin sheet of goldfoil: most go through(empty space). Somedeflect or bounce off(small + chargednucleus).
website
Bohr Model
(c) 2006, Mark Rosengarten
Electrons orbit around the nucleus in energy levels (shells). Atomic bright-line spectra was the clue. Animation
Quantum-Mechanical Model
(c) 2006, Mark Rosengarten
Electron energy levels are wave functions. Electrons are found in orbitals, regions of space
where an electron is most likely to be found. You can’t know both where the electron is and
where it is going at the same time. Electrons buzz around the nucleus like gnats
buzzing around your head.
Matter
(c) 2006, Mark Rosengarten
1) Properties of Phases2) Types of Matter3) Phase Changes
Properties of Phases
(c) 2006, Mark Rosengarten
Solids: Crystal lattice (regular geometric pattern), vibration motion only
Liquids: particles flow past each other but are still attracted to each other.
Gases: particles are small and far apart, they travel in a straight line until they hit something, they bounce off without losing any energy, they are so far apart from each other that they have effectively no attractive forces and their speed is directly proportional to the Kelvin temperature (Kinetic-Molecular Theory, Ideal Gas Theory)
Solids
(c) 2006, Mark Rosengarten
The positive and negative ions alternate in the ionic crystal latticeof NaCl.
Liquids
(c) 2006, Mark Rosengarten
When heated, the ions movefaster and eventuallyseparate from each other to form a liquid. The ions areloosely held together by theoppositely charged ions, butthe ions are moving too fastfor the crystal lattice to staytogether.
Gases
(c) 2006, Mark Rosengarten
Since all gas molecules spread outthe same way, equal volumes of gas under equal conditions of temperature and pressure will contain equal numbers of molecules of gas. 22.4 L of any gas at STP (1.00 atm and 273K)will contain one mole (6.02 X 1023) gas molecules.
Since there is space between gasmolecules, gases are affected bychanges in pressure.
Types of Matter
(c) 2006, Mark Rosengarten
Substances (Homogeneous) Elements (cannot be decomposed by chemical
change): Al, Ne, O, Br, H Compounds (can be decomposed by chemical
change): NaCl, Cu(ClO3)2, KBr, H2O, C2H6
Mixtures Homogeneous: Solutions (solvent + solute) Heterogeneous: soil, Italian dressing, etc.
Elements
(c) 2006, Mark Rosengarten
A sample of lead atoms (Pb). All atoms in the sample consist of lead, so the substance is homogeneous.
A sample of chlorine atoms (Cl). All atoms in the sample consist of chlorine, so the substance is homogeneous.
website
Compounds
(c) 2006, Mark Rosengarten
Lead has two charges listed, +2 and +4. This is a sample of lead (II) chloride (PbCl2). Two or more elements bonded in a whole-number ratio is a COMPOUND.
This compound is formed from the +4 version of lead. This is lead (IV) chloride (PbCl4). Notice how both samples of lead compounds have consistent composition throughout? Compounds are homogeneous!
website
Mixtures
(c) 2006, Mark Rosengarten
A mixture of lead atoms and chlorine atoms. They exist in no particular ratio and are not chemically combined with each other. They can be separated by physical means.
A mixture of PbCl2 and PbCl4 formula units. Again, they are in no particular ratio to each other and can be separated without chemical change.
website
Phase Changes
(c) 2006, Mark Rosengarten
Phase Change Types Phase Change Diagrams Heat of Phase Change Evaporation
Phase Change Types
(c) 2006, Mark Rosengarten
website
Phase Change Diagrams
(c) 2006, Mark Rosengarten
AB: Solid PhaseBC: Melting (S + L)CD: Liquid PhaseDE: Boiling (L + G)EF: Gas Phase
Notice how temperature remains constant during a phase change? That’s because the PE is changing, not the KE.
website
Heat of Phase Change
(c) 2006, Mark Rosengarten
How many joules would it take to melt 100. g of H2O (s) at 0oC?
q=mHf = (100. g)(334 J/g) = 33400 J How many joules would it take to boil 100. g of H2O
(l) at 100oC? q=mHv = (100.g)(2260 J/g) = 226000 J
website
Evaporation
(c) 2006, Mark Rosengarten
When the surface molecules of a gas travel upwards at a great enough speed to escape.
The pressure a vapor exerts when sealed in a container at equilibrium is called vapor pressure, and can be found on Table H.
When the liquid is heated, its vapor pressure increases.
When the liquid’s vapor pressure equals the pressure exerted on it by the outside atmosphere, the liquid can boil.
If the pressure exerted on a liquid increases, the boiling point of the liquid increases (pressure cooker). If the pressure decreases, the boiling point of the liquid decreases (special cooking directions for high elevations).
Reference Table H: Vapor Pressure of Four Liquids
(c) 2006, Mark Rosengarten
website
Bonding
(c) 2006, Mark Rosengarten
1) The Periodic Table2) Ions3) Ionic Bonding4) Covalent Bonding5) Metallic Bonding
The Periodic Table
(c) 2006, Mark Rosengarten
Metals Nonmetals Metalloids Chemistry of Groups Electronegativity Ionization Energy
Video
Metals
(c) 2006, Mark Rosengarten
Have luster, are malleable and ductile, good conductors of heat and electricity
Lose electrons to nonmetal atoms to form positively charged ions in ionic bonds
Large atomic radii compared to nonmetal atoms
Low electronegativity and ionization energy
Left side of the periodic table (except H)
Nonmetals
(c) 2006, Mark Rosengarten
Are dull and brittle, poor conductors Gain electrons from metal atoms to form neg
atively charged ions in ionic bonds
Share unpaired valence electrons with other nonmetal atoms to form covalent bonds and molecules
Small atomic radii compared to metal atoms High electronegativity and ionization energy Right side of the periodic table (except Group
18)
Metalloids
(c) 2006, Mark Rosengarten
Found lying on the jagged line between metals and nonmetals flatly touching the line (except Al and Po).
Share properties of metals and nonmetals (Si is shiny like a metal, brittle like a nonmetal and is a semiconductor).
Chemistry of Groups
(c) 2006, Mark Rosengarten
Group 1: Alkali Metals Group 2: Alkaline Earth Metals Groups 3-11: Transition Elements Group 17: Halogens Group 18: Noble Gases
Diatomic Molecules
website
Group 1: Alkali Metals
(c) 2006, Mark Rosengarten
Most active metals, only found in compounds in nature
React violently with water to form hydrogen gas and a strong base: 2 Na (s) + H2O (l) 2 NaOH (aq) + H2 (g)
1 valence electron Form +1 ion by losing that valence
electron Form oxides like Na2O, Li2O, K2O
Group 2: Alkaline Earth Metals
(c) 2006, Mark Rosengarten
Very active metals, only found in compounds in nature
React strongly with water to form hydrogen gas and a base: Ca (s) + 2 H2O (l) Ca(OH)2 (aq) + H2
(g) 2 valence electrons Form +2 ion by losing those valence
electrons Form oxides like CaO, MgO, BaO
Groups 3-11: Transition Metals
(c) 2006, Mark Rosengarten
Many can form different possible charges of ions If there is more than one ion listed, give the
charge as a Roman numeral after the name Cu+1 = copper (I) Cu+2 = copper (II) Compounds containing these metals can be
colored.
Group 17: Halogens
(c) 2006, Mark Rosengarten
Most reactive nonmetals React violently with metal atoms to form
halide compounds: 2 Na + Cl2 2 NaCl Only found in compounds in nature Have 7 valence electrons Gain 1 valence electron from a metal to
form -1 ions Share 1 valence electron with another
nonmetal atom to form one covalent bond.
Group 18: Noble Gases
(c) 2006, Mark Rosengarten
Are completely nonreactive since they have eight valence electrons, making a stable octet.
Kr and Xe can be forced, in the laboratory, to give up some valence electrons to react with fluorine.
Since noble gases do not naturally bond to any other elements, one atom of noble gas is considered to be a molecule of noble gas. This is called a monatomic molecule. Ne represents an atom of Ne and a molecule of Ne.
Diatomic Molecules(elements)
(c) 2006, Mark Rosengarten
Br, I, N, Cl, H, O and F are so reactive that they exist in a more chemically stable state when they covalently bond with another atom of their own element to make two-atom, or diatomic molecules.
Br2, I2, N2, Cl2, H2, O2 and F2
The decomposition of water: 2 H2O 2 H2 + O2
Electronegativity
(c) 2006, Mark Rosengarten
An atom’s attraction to electrons in a chemical bond. F has the highest, at 4.0 Fr has the lowest, at 0.7 If two atoms that are different in EN (END) from each
other by 1.7 or more collide and bond (like a metal atom and a nonmetal atom), the one with the higher electronegativity will pull the valence electrons away from the atom with the lower electronegativity to form a (-) ion. The atom that was stripped of its valence electrons forms a (+) ion.
If the two atoms have an END of less than 1.7, they will share their unpaired valence electrons…covalent bond!
website
Ionization Energy
(c) 2006, Mark Rosengarten
The energy required to remove the most loosely held valence electron from an atom in the gas phase.
High electronegativity means high ionization energy because if an atom is more attracted to electrons, it will take more energy to remove those electrons.
Metals have low ionization energy. They lose electrons easily to form (+) charged ions.
Nonmetals have high ionization energy but high electronegativity. They gain electrons easily to form (-) charged ions when reacted with metals, or share unpaired valence electrons with other nonmetal atoms.
website
Ions
(c) 2006, Mark Rosengarten
Ions are charged particles formed by the gain or loss of electrons. Metals lose electrons (oxidation) to form (+)
charged cations. Nonmetals gain electrons (reduction) to form (-)
charged anions. Atoms will gain or lose electrons in such a way
that they end up with 8 valence electrons (stable octet). The exceptions to this are H, Li, Be and B, which
are not large enough to support 8 valence electrons. They must be satisfied with 2 (Li, Be, B) or 0 (H).
website
Metal Ions (Cations-positive ion)
(c) 2006, Mark Rosengarten
Na: 2-8-1
Na+1: 2-8
Ca: 2-8-8-2
Ca+2: 2-8-8
Al: 2-8-3
Al+3: 2-8
Note that when the atom loses its valence electron, the next lower PEL becomes the valence PEL.
Notice how the dot diagrams for metal ions lack dots! Place brackets around the element symbol and put the charge on the upper right outside!
Nonmetal Ions (Anions-negative ion)
(c) 2006, Mark Rosengarten
F: 2-7 F-1: 2-8
O: 2-6 O-2: 2-8
N: 2-5 N-3: 2-8
Note how the ions all have 8 valence electrons. Also note the gained electrons as red dots. Nonmetal ion dot diagrams show 8 dots, with brackets around the dot diagram and the charge of the ion written to the upper right side outside the brackets.
Ionic Bonding
(c) 2006, Mark Rosengarten
If two atoms that are different in ELECTRONEGATIVITY (END) from each other by 1.7 or more collide and bond (like a metal atom and a nonmetal atom), the one with the higher electronegativity will pull the valence electrons away from the atom with the lower electronegativity to form a (-) ion. The atom that was stripped of its valence electrons forms a (+) ion.
The oppositely charged ions attract to form the bond. It is a surface bond that can be broken by melting or dissolving in water.
Ionic bonding forms ionic crystal lattices, not molecules.
website
Example of Ionic Bonding
(c) 2006, Mark Rosengarten
Covalent Bonding
(c) 2006, Mark Rosengarten
If two nonmetal atoms have an END of 1.7 or less, they will share their unpaired valence electrons to form a covalent bond.
A particle made of covalently bonded nonmetal atoms is called a molecule.
If the END is between 0 and 0.4, the sharing of electrons is equal, so there are no charged ends. This is NONPOLAR covalent bonding.
If the END is between 0.5 and 1.7, the sharing of electrons is unequal. The atom with the higher EN will be - and the one with the lower EN will be + charged. This is a POLAR covalent bonding. (means “partial”)
Video
Examples of Covalent Bonding
(c) 2006, Mark Rosengarten
website
Metallic Bonding
(c) 2006, Mark Rosengarten
Metal atoms of the same element bond with each other by sharing valence electrons that they lose to each other.
This is a lot like an atomic game of “hot potato”, where metal kernals (the atom inside the valence electrons) sit in a crystal lattice, passing valence electrons back and forth between each other).
Since electrons can be forced to travel in a certain direction within the metal, metals are very good at conducting electricity in all phases.
website
Compounds
(c) 2006, Mark Rosengarten
1) Types of Compounds2) Formula Writing3) Formula Naming4) Empirical Formulas5) Molecular Formulas6) Types of Chemical Reactions7) Balancing Chemical Reactions8) Attractive Forces
Types of Compounds
(c) 2006, Mark Rosengarten
Ionic: made of metal and nonmetal ions. Form an ionic crystal lattice when in the solid phase. Ions separate when melted or dissolved in water, allowing electrical conduction (electrolytes-video). Examples: NaCl, K2O, CaBr2
Molecular: made of nonmetal atoms bonded to form a distinct particle called a molecule. Bonds do not break upon melting or dissolving, so molecular substances do not conduct electricity. EXCEPTION: Acids [H+A- (aq)] ionize in water to form H3O+ and A-, so they do conduct.
Network: made up of nonmetal atoms bonded in a seemingly endless matrix of covalent bonds with no distinguishable molecules. Very high m.p., don’t conduct.
website
Ionic Compounds
(c) 2006, Mark Rosengarten
Ionic Crystal Structure, then adding heat (or dissolving in water) to breakup the crystal into a liquid composed of free-moving ions.
website
Molecular Compounds
(c) 2006, Mark Rosengarten
website
Network Solids
(c) 2006, Mark Rosengarten
Network solids are made of nonmetal atoms covalently bonded together to form large crystal lattices. No individual molecules can be distinguished. Examples include C (diamond) and SiO2 (quartz). Corundum (Al2O3) also forms these, even though Al is considered a metal. Network solids are among the hardest materials known. They have extremely high melting points and do not conduct electricity.
Formula Writing
(c) 2006, Mark Rosengarten
The charge of the (+) ion and the charge of the (-) ion must cancel out to make the formula. Use subscripts to indicate how many atoms of each element there are in the compound, no subscript if there is only one atom of that element.
Na+1 and Cl-1 = NaCl Ca+2 and Br-1 = CaBr2
Al+3 and O-2 = Al2O3
Zn+2 and PO4-3 = Zn3(PO4)2
Try these problems!
website
Formulas to Write
(c) 2006, Mark Rosengarten
Ba+2 and N-3
NH4+1 and SO4
-2
Li+1 and S-2
Cu+2 and NO3-1
Al+3 and CO3-2
Fe+3 and Cl-1
Pb+4 and O-2
Pb+2 and O-2
Formula Naming
(c) 2006, Mark Rosengarten
Compounds are named from the elements or polyatomic ions that form them.
KCl = potassium chloride Na2SO4 = sodium sulfate
(NH4)2S = ammonium sulfide
AgNO3 = silver nitrate
Notice all the metals listed here only have one charge listed? So what do you do if a metal has more than one charge listed? Take a peek!
The Stock System
(c) 2006, Mark Rosengarten
CrCl2 = chromium (II) chloride Try
CrCl3 = chromium (III) chloride Co(NO3)2 and
CrCl6 = chromium (VI) chloride Co(NO3)3
FeO = iron (II) oxide MnS = manganese (II) sulfide Fe2O3 = iron (III) oxide MnS2 = manganese (IV) sulfide The Roman numeral is the charge of the metal ion!
website
Empirical Formulas
(c) 2006, Mark Rosengarten
Ionic formulas: represent the simplest whole number mole ratio of elements in a compound.
Ca3N2 means a 3:2 ratio of Ca ions to N ions in the compound.
Many molecular formulas can be simplified to empirical formulas Ethane (C2H6) can be simplified to CH3. This is
the empirical formula…the ratio of C to H in the molecule.
All ionic compounds have empirical formulas.
website
Molecular Formulas
(c) 2006, Mark Rosengarten
The count of the actual number of atoms of each element in a molecule.
H2O: a molecule made of two H atoms and one O atom covalently bonded together.
C2H6O: A molecule made of two C atoms, six H atoms and one O atom covalently bonded together.
Molecular formulas are whole-number multiples of empirical formulas: H2O = 1 X (H2O) C8H16 = 8 X (CH2)
Calculating Molecular Formulas
Types of Chemical Reactions
(c) 2006, Mark Rosengarten
Redox Reactions: driven by the loss (oxidation) and gain (reduction) of electrons. Any species that does not change charge is called the spectator ion. Synthesis Decomposition Single Replacement
Ion Exchange Reaction: driven by the formation of an insoluble precipitate. The ions that remain dissolved throughout are the spectator ions. Double Replacement
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website
Synthesis
(c) 2006, Mark Rosengarten
Two elements combine to form a compound 2 Na + O2 Na2O Same reaction, with charges added in:
2 Na0 + O20 Na2
+1O-2
Na0 is oxidized (loses electrons), is the reducing agent O2
0 is reduced (gains electrons), is the oxidizing agent
Electrons are transferred from the Na0 to the O20.
No spectator ions, there are only two elements here.
Decomposition
(c) 2006, Mark Rosengarten
A compound breaks down into its original elements. Na2O 2 Na + O2
Same reaction, with charges added in: Na2
+1O-2 2 Na0 + O20
O-2 is oxidized (loses electrons), is the reducing agent Na+1 is reduced (gains electrons), is the oxidizing agent
Electrons are transferred from the O-2 to the Na+1.
No spectator ions, there are only two elements here.
Single Replacement
(c) 2006, Mark Rosengarten
An element replaces the same type of element in a compound.
Ca + 2 KCl CaCl2 + 2 K Same reaction, with charges added in:
Ca0 + 2 K+1Cl-1 Ca+2Cl2-1 + 2 K0
Ca0 is oxidized (loses electrons), is the reducing agent K+1 is reduced (gains electrons), is the oxidizing agent
Electrons are transferred from the Ca0 to the K+1.
Cl-1 is the spectator ion, since it’s charge doesn’t change.
Double Replacement
(c) 2006, Mark Rosengarten
The (+) ion of one compound bonds to the (-) ion of another compound to make an insoluble precipitate. The compounds must both be dissolved in water to break the ionic bonds first.
NaCl (aq) + AgNO3 (aq) NaNO3 (aq) + AgCl (s) The Cl-1 and Ag+1 come together to make the
insoluble precipitate, which looks like snow in the test tube.
No species change charge, so this is not a redox reaction.
Since the Na+1 and NO3-1 ions remain dissolved
throughout the reaction, they are the spectator ions. How do identify the precipitate?
Identifying the Precipitate
(c) 2006, Mark Rosengarten
The precipitate is the compound that is insoluble. AgCl is a precipitate because Cl- is a halide. Halides are soluble, except when combined with Ag+ and others.
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Balancing Chemical Reactions
(c) 2006, Mark Rosengarten
Balance one element or ion at a time Use a pencil Use coefficients only, never change
subscripts(formulas) Revise if necessary
The coefficient multiplies everything in the formula by that amount 2 Ca(NO3)2 means that you have 2 Ca, 4 N and
12 O. Examples for you to try!website website
Reactions to Balance
(c) 2006, Mark Rosengarten
___NaCl ___Na + ___Cl2
___Al + ___O2 ___Al2O3
___SO3 ___SO2 + ___O2
___Ca + ___HNO3 ___Ca(NO3)2 + ___H2
__FeCl3 + __Pb(NO3)2 __Fe(NO3)3 + __PbCl2
Attractive Forces
(c) 2006, Mark Rosengarten
Molecules have partially charged ends. The + end of one molecule attracts to the - end of another molecule.
Ions are charged (+) or (-). Positively charged ions attract other to form ionic bonds, a type of attractive force.
Since partially charged ends result in weaker attractions than fully charged ends, ionic compounds generally have much higher melting points than molecular compounds.
Determining Polarity of Molecules Hydrogen Bond Attractions
Determining Polarity ofMolecules
(c) 2006, Mark Rosengarten
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Hydrogen BondAttractions
(c) 2006, Mark Rosengarten
A hydrogen bond attraction is a very strong attractive force between the H end of one polar molecule and the N, O or F end of another polar molecule. This attraction is so strong that water is a liquid at a temperature where most compounds that are much heavier than water (like propane, C3H8) are gases. This also gives water its surface tension and its ability to form a meniscus in a narrow glass tube.
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Math of Chemistry
(c) 2006, Mark Rosengarten
1) Formula Mass2) Percent Composition3) Mole Problems4) Gas Laws5) Neutralization6) Concentration7) Significant Figures and Rounding8) Metric Conversions9) Calorimetry
Formula Mass
(c) 2006, Mark Rosengarten
Gram Formula Mass = sum of atomic masses of all elements in the compound
Round given atomic masses to the nearest tenth H2O: (2 X 1.0) + (1 X 16.0) = 18.0 grams/mole
Na2SO4: (2 X 23.0)+(1 X 32.1)+(4 X 16.0) = 142.1 g/mole
Now you try: BaBr2
CaSO4
Al2(CO3)3 websiteVideo
Percent Composition
(c) 2006, Mark Rosengarten
What is the % composition, by mass,of each element in SiO2?
%Si = (28.1/60.1) X 100 = 46.8%%O = (2 X 16.0 = 32.0), (32.0/60.1) X 100 = 53.2%
The mass of part is the number of atoms of that element in the compound. The mass of whole is the formula mass of the compound. Don’t forget to take atomic mass to the nearest tenth! This is a problem for you to try.
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Practice PercentComposition Problem
(c) 2006, Mark Rosengarten
What is the percent by mass of each element in Li2SO4?
Mole Problems
(c) 2006, Mark Rosengarten
Grams <=> Moles Molecular Formula Stoichiometry
Grams <=> Moles
(c) 2006, Mark Rosengarten
How many grams will 3.00 moles of NaOH (40.0 g/mol) weigh?
3.00 moles X 40.0 g/mol = 120. g
How many moles of NaOH (40.0 g/mol) are represented by 10.0 grams?
(10.0 g) / (40.0 g/mol) = 0.250 molVideo
Molecular Formula
(c) 2006, Mark Rosengarten
Molecular Formula = (Molecular Mass/Empirical Mass) X Empirical Formula
What is the molecular formula of a compound with an empirical formula of CH2 and a molecular mass of 70.0 grams/mole?
1) Find the Empirical Formula Mass: CH2 = 14.0 2) Divide the MM/EM: 70.0/14.0 = 5 3) Multiply the molecular formula by the result:
5 (CH2) = C5H10
Stoichiometry
(c) 2006, Mark Rosengarten
Moles of Target = Moles of Given X (Coefficent of Target/Coefficient of given)
Given the balanced equation N2 + 3 H2 2 NH3, How many moles of H2 need to be completely reacted with N2 to yield 20.0 moles of NH3?
20.0 moles NH3 X (3 H2 / 2 NH3) = 30.0 moles H2
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Gas Laws
(c) 2006, Mark Rosengarten
Make a data table to put the numbers so you can eliminate the words.
Make sure that any Celsius temperatures are converted to Kelvin (add 273).
Rearrange the equation before substituting in numbers. If you are trying to solve for T2, get it out of the denominator first by cross-multiplying.
If one of the variables is constant, then eliminate it. Try these problems! website
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Gas Law Problem 1
(c) 2006, Mark Rosengarten
A 2.00 L sample of N2 gas at STP is compressed to 4.00 atm at constant temp-erature. What is the new volume of the gas?
V2 = P1V1 / P2 = (1.00 atm)(2.00 L) /
(4.00 atm) = 0.500 L
Gas Law Problem 2
(c) 2006, Mark Rosengarten
To what temperature must a 3.000 L sample of O2 gas at 300.0 K be heated to raise the volume to 10.00 L?
T2 = V2T1/V1
= (10.00 L)(300.0 K) / (3.000 L) = 1000. K
Gas Law Problem 3
(c) 2006, Mark Rosengarten
A 3.00 L sample of NH3 gas at 100.0 kPa is cooled from 500.0 K to 300.0 K and its pressure is reduced to 80.0 kPa. What is the new volume of the gas?
V2 = P1V1T2 / P2T1
= (100.0 kPa)(3.00 L)(300. K) / (80.0 kPa)(500. K) = 2.25 L
Neutralization
(c) 2006, Mark Rosengarten
10.0 mL of 0.20 M HCl is neutralized by 40.0 mL of NaOH. What is the concentration of the NaOH?
#H MaVa = #OH MbVb, so Mb = #H MaVa / #OH Vb
= (1)(0.20 M)(10.0 mL) / (1) (40.0 mL) = 0.050 M
How many mL of 2.00 M H2SO4 are needed to completely neutralize 30.0 mL of 0.500 M KOH?
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Concentration
(c) 2006, Mark Rosengarten
Molarity Parts per Million Percent by Mass Percent by Volume
Molarity
(c) 2006, Mark Rosengarten
What is the molarity of a 500.0 mL solution of NaOH (FM = 40.0) with 60.0 g of NaOH (aq)? Convert g to moles and mL to L first! M = moles / L = 1.50 moles / 0.5000 L = 3.00 M
How many grams of NaOH does it take to make 2.0 L of a 0.100 M solution of NaOH (aq)? Moles = M X L = 0.100 M X 2.0 L = 0.200 moles Convert moles to grams: 0.200 moles X 40.0 g/mol = 8.00
g
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Parts Per Million
(c) 2006, Mark Rosengarten
100.0 grams of water is evaporated and analyzed for lead. 0.00010 grams of lead ions are found. What is the concentration of the lead, in parts per million?
ppm = (0.00010 g) / (100.0 g) X 1 000 000 = 1.0 ppm If the legal limit for lead in the water is 3.0 ppm,
then the water sample is within the legal limits (it’s OK!)
Percent by Mass
(c) 2006, Mark Rosengarten
A 50.0 gram sample of a solution is evaporated and found to contain 0.100 grams of sodium chloride. What is the percent by mass of sodium chloride in the solution?
% Comp = (0.100 g) / (50.0 g) X 100 = 0.200%
Percent By Volume
(c) 2006, Mark Rosengarten
Substitute “volume” for “mass” in the above equation.
What is the percent by volume of hexane if 20.0 mL of hexane are dissolved in benzene to a total volume of 80.0 mL?
% Comp = (20.0 mL) / (80.0 mL) X100 = 25.0%
Sig Figs and Rounding
(c) 2006, Mark Rosengarten
How many Significant Figures does a number have?
What is the precision of my measurement?
How do I round off answers to addition and subtraction problems?
How do I round off answers to multiplication and division problems?
How many Sig Figs?
Start counting sig figs at the first non-zero. All digits except place-holding zeroes are sig
figs.
Measurement # of Sig Figs
234 cm 3
67000 cm 2
_ 45000 cm
4
560. cm 3
560.00 cm 5
Measurement # of Sig Figs
0.115 cm 3
0.00034 cm 2
0.00304 cm 3
0.0560 cm 3
0.00070700 cm 5
(c) 2006, Mark Rosengarten
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What Precision?
(c) 2006, Mark Rosengarten
A number’s precision is determined by the furthest (smallest) place the number is recorded to.
6000 mL : thousands place 6000. mL : ones place 6000.0 mL : tenths place 5.30 mL : hundredths place 8.7 mL : tenths place 23.740 mL : thousandths place
Rounding with addition and subtraction
(c) 2006, Mark Rosengarten
Answers are rounded to the least precise place.
1) 4.732 cm 2) 17.440 mL 3) 32.0 MW 16.8 cm 3.895 mL + 0.0059 MW + 0.781 cm + 16.77 mL --------------- ---------- -------------- 22.313 cm 38.105 mL 32.0059 MW 22.3 cm 38.11 mL 32.0 MW
Rounding with multiplicationand division
(c) 2006, Mark Rosengarten
Answers are rounded to the fewest number of significant figures.
1) 37.66 KW 2) 14.922 cm 3) 98.11 kg x 2.2 h x 2.0 cm x 200 m ---------- ----------- ---------- 82.852 KWh 29.844 cm2 19 622 kgm 83 KWh 30. cm2 20 000 kgm
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Metric Conversions
(c) 2006, Mark Rosengarten
Determine how many powers of ten difference there are between the two units (no prefix = 100) and create a conversion factor. Multiply or divide the given by the conversion factor.
How many kg are in 38.2 cg?
(38.2 cg) /(100000 cg/kg) = 0.000382 km
How many mL in 0.988 dL?
(0.988 dg) X (100 mL/dL) = 98.8 mL
Calorimetry
(c) 2006, Mark Rosengarten
This equation can be used to determine any of the variables here. You will not have to solve for C, since we will always assume that the energy transfer is being absorbed by or released by a measured quantity of water, whose specific heat is given above.
Solving for q Solving for m Solving for DT
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Solving for q
(c) 2006, Mark Rosengarten
How many joules are absorbed by 100.0 grams of water in a calorimeter if the temperature of the water increases from 20.0oC to 50.0oC?
q = mCDT = (100.0 g)(4.18 J/goC)(30.0oC) = 12500 J
Solving for m
(c) 2006, Mark Rosengarten
A sample of water in a calorimeter cup increases from 25oC to 50.oC by the addition of 500.0 joules of energy. What is the mass of water in the calorimeter cup?
q = mCDT, so m = q / CDT = (500.0 J) / (4.18 J/goC)(25oC) = 4.8 g
Solving for DT
(c) 2006, Mark Rosengarten
If a 50.0 gram sample of water in a calorimeter cup absorbs 1000.0 joules of energy, how much will the temperature rise by?
q = mCDT, so DT = q / mC = (1000.0 J)/(50.0 g)(4.18 J/goC) = 4.8oC
If the water started at 20.0oC, what will the final temperature be? Since the water ABSORBS the energy, its temperature will
INCREASE by the DT: 20.0oC + 4.8oC = 24.8oC
Kinetics and Thermodynamics
(c) 2006, Mark Rosengarten
1) Reaction Rate2) Heat of Reaction3) Potential Energy Diagrams4) Equilibrium5) Le Châtelier’s Principle6) Solubility Curves
Reaction Rate
(c) 2006, Mark Rosengarten
Reactions happen when reacting particles collide with sufficient energy (activation energy) and at the proper angle.
Anything that makes more collisions in a given time will make the reaction rate increase. Increasing temperature Increasing concentration (pressure for gases) Increasing surface area (solids)
Adding a catalyst makes a reaction go faster by removing steps from the mechanism and lowering the activation energy without getting used up in the process.
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Heat of Reaction
(c) 2006, Mark Rosengarten
Reactions either absorb PE (endothermic, +DH) or release PE (exothermic, -DH)
Exothermic, PEKE, Temp
Endothermic, KEPE, Temp
Rewriting the equation with heat included:
4 Al(s) + 3 O2(g) 2 Al2O3(s) + 3351 kJ
N2(g) + O2(g) +182.6 kJ 2 NO(g)
Potential Energy Diagrams
(c) 2006, Mark Rosengarten
Steps of a reactions: Reactants have a certain amount of PE stored
in their bonds (Heat of Reactants) The reactants are given enough energy to
collide and react (Activation Energy) The resulting intermediate has the highest
energy that the reaction can make (Heat of Activated Complex)
The activated complex breaks down and forms the products, which have a certain amount of PE stored in their bonds (Heat of Products)
Hproducts - Hreactants = DH EXAMPLES
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Making a PE Diagram
(c) 2006, Mark Rosengarten
X axis: Reaction Coordinate (time, no units) Y axis: PE (kJ) Three lines representing energy (Hreactants, Hactivated
complex, Hproducts) Two arrows representing energy changes:
From Hreactants to Hactivated complex: Activation Energy From Hreactants to Hproducts : DH
ENDOTHERMIC PE DIAGRAM EXOTHERMIC PE DIAGRAM
Endothermic PE Diagram
(c) 2006, Mark Rosengarten
If a catalyst is added?
Endothermic with Catalyst
(c) 2006, Mark Rosengarten
The red line represents the catalyzed reaction.
Exothermic PE Diagram
(c) 2006, Mark RosengartenWhat does it look like with a catalyst?
Exothermic with a Catalyst
(c) 2006, Mark Rosengarten
The red line represents the catalyzed reaction. Lower A.E. and faster reaction time!
Equilibrium
(c) 2006, Mark Rosengarten
When the rate of the forward reaction equals the rate of the reverse reaction.
Examples of Equilibrium
(c) 2006, Mark Rosengarten
Solution Equilibrium: when a solution is saturated, the rate of dissolving equals the rate of precipitating. NaCl (s) Na+1 (aq) + Cl-1 (aq)
Vapor-Liquid Equilibrium: when a liquid is trapped with air in a container, the liquid evaporates until the rate of evaporation equals the rate of condensation. H2O (l) H2O (g)
Phase equilibrium: At the melting point, the rate of solid turning to liquid equals the rate of liquid turning back to solid. H2O (s) H2O (l)
Le Châtelier’s Principle
(c) 2006, Mark Rosengarten
If a system at equilibrium is stressed, the equilibrium will shift in a direction that relieves that stress.
A stress is a factor that affects reaction rate. Since catalysts affect both reaction rates equally, catalysts have no effect on a system already at equilibrium.
Equilibrium will shift AWAY from what is added Equilibrium will shift TOWARDS what is removed. This is because the shift will even out the change in
reaction rate and bring the system back to equilibrium
NEXT Video
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Steps to Relieving Stress
(c) 2006, Mark Rosengarten
1) Equilibrium is subjected to a STRESS. 2) System SHIFTS towards what is removed from
the system or away from what is added. The shift results in a CHANGE OF CONCENTRATION
for both the products and the reactants. If the shift is towards the products, the
concentration of the products will increase and the concentration of the reactants will decrease.
If the shift is towards the reactants, the concentration of the reactants will increase and the concentration of the products will decrease.
NEXT
Examples
(c) 2006, Mark Rosengarten
For the reaction N2(g) + 3H2(g) 2 NH3(g) + heat Adding N2 will cause the equilibrium to shift RIGHT,
resulting in an increase in the concentration of NH3 and a decrease in the concentration of N2 and H2.
Removing H2 will cause a shift to the LEFT, resulting in a decrease in the concentration of NH3 and an increase in the concentration of N2 and H2.
Increasing the temperature will cause a shift to the LEFT, same results as the one above.
Decreasing the pressure will cause a shift to the LEFT, because there is more gas on the left side, and making more gas will bring the pressure back up to its equilibrium amount.
Adding a catalyst will have no effect, so no shift will happen.
Solubility Curves
(c) 2006, Mark Rosengarten
Solubility: the maximum quantity of solute that can be dissolved in a given quantity of solvent at a given temperature to make a saturated solution.
Saturated: a solution containing the maximum quantity of solute that the solvent can hold. The limit of solubility.
Supersaturated: the solution is holding more than it can theoretically hold OR there is excess solute which precipitates out. True supersaturation is rare.
Unsaturated: There are still solvent molecules available to dissolve more solute, so more can dissolve.
How ionic solutes dissolve in water: polar water molecules attach to the ions and tear them off the crystal. LIKE DISSOLVES LIKE
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Solubility
(c) 2006, Mark Rosengarten
Solubility: go to the temperature and up to the desired line, then across to the Y-axis. This is how many g of solute are needed to make a saturated solution of that solute in 100g of H2O at that particular temperature.
At 40oC, the solubility of KNO3 in 100g of water is 64 g. In 200g of water, double that amount. In 50g of water, cut it in half.
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Supersaturated
(c) 2006, Mark Rosengarten
If 120 g of NaNO3 are added to 100g of water at 30oC:
1) The solution would be SUPERSATURATED, because there is more solute dissolved than the solubility allows
2) The extra 25g would precipitate out
3) If you heated the solution up by 24oC (to 54oC), the excess solute would dissolve.
Unsaturated
(c) 2006, Mark Rosengarten
If 80 g of KNO3 are added to 100g of water at 60oC:
1) The solution would be UNSATURATED, because there is less solute dissolved than the solubility allows
2) 26g more can be added to make a saturated solution
3) If you cooled the solution down by 12oC (to 48oC), the solution would become saturated
How Ionic Solutes Dissolve in Water
(c) 2006, Mark Rosengarten
Water solvent molecules attach to the ions (H end to the Cl-, O end to the Na+)
Water solvent holds the ions apart and keeps the ions from coming back together
Acids and Bases
(c) 2006, Mark Rosengarten
1) Formulas, Naming and Properties of Acids2) Formulas, Naming and Properties of Bases3) Neutralization4) pH5) Indicators6) Alternate Theories
Formulas, Naming and Properties of Acids
(c) 2006, Mark Rosengarten
Arrhenius Definition of Acids: molecules that dissolve in water to produce H3O+ (hydronium) as the only positively charged ion in solution.
HCl (g) + H2O (l) H3O+ (aq) + Cl-
Properties of Acids Naming of Acids Formula Writing of Acids
Properties of Acids
(c) 2006, Mark Rosengarten
Acids react with metals above H2 on Table J to form H2(g) and a salt.
Acids have a pH of less than 7. Dilute solutions of acids taste sour. Acids turn phenolphthalein CLEAR, litmus
RED and bromthymol blue YELLOW. Acids neutralize bases. Acids are formed when acid anhydrides
(NO2, SO2, CO2) react with water for form acids. This is how acid rain forms from auto and industrial emissions.
Naming of Acids
(c) 2006, Mark Rosengarten
Binary Acids (H+ and a nonmetal) hydro (nonmetal) -ide + ic acid
HCl (aq) = hydrochloric acid Ternary Acids (H+ and a
polyatomic ion) (polyatomic ion) -ate +ic acid
HNO3 (aq) = nitric acid
(polyatomic ion) -ide +ic acid HCN (aq) = cyanic acid
(polyatomic ion) -ite +ous acid HNO2 (aq) = nitrous acid
Formula Writing of Acids
(c) 2006, Mark Rosengarten
Acids formulas get written like any other. Write the H+1 first, then figure out what the negative ion is based on the name. Cancel out the charges to write the formula. Don’t forget the (aq) after it…it’s only an acid if it’s in water!
Hydrosulfuric acid: H+1 and S-2 = H2S (aq)
Carbonic acid: H+1 and CO3-2 = H2CO3 (aq)
Chlorous acid: H+1 and ClO2-1 = HClO2 (aq)
Hydrobromic acid: H+1 and Br-1 = HBr (aq) Hydronitric acid: Hypochlorous acid: Perchloric acid:
Formulas, Naming and Properties of Bases
(c) 2006, Mark Rosengarten
Arrhenius Definition of Bases: ionic compounds that dissolve in water to produce OH- (hydroxide) as the only negatively charged ion in solution.
NaOH (s) Na+1 (aq) + OH-1 (aq)
Properties of Bases Naming of Bases Formula Writing of Bases
Properties of Bases
(c) 2006, Mark Rosengarten
Bases react with fats to form soap and glycerol. This process is called saponification.
Bases have a pH of more than 7. Dilute solutions of bases taste bitter. Bases turn phenolphthalein PINK, litmus BLUE and
bromthymol blue BLUE. Bases neutralize acids. Bases are formed when alkali metals or alkaline
earth metals react with water. The words “alkali” and “alkaline” mean “basic”, as opposed to “acidic”.
Naming of Bases
(c) 2006, Mark Rosengarten
Bases are named like any ionic compound, the name of the metal ion first (with a Roman numeral if necessary) followed by “hydroxide”.Fe(OH)2 (aq) = iron (II) hydroxide
Fe(OH)3 (aq) = iron (III) hydroxide
Al(OH)3 (aq) = aluminum hydroxide
NH3 (aq) is the same thing as NH4OH:
NH3 + H2O NH4OH
Also called ammonium hydroxide.
Formula Writing of Bases
(c) 2006, Mark Rosengarten
Formula writing of bases is the same as for any ionic formula writing. The charges of the ions have to cancel out.
Calcium hydroxide = Ca+2 and OH-1 = Ca(OH)2 (aq) Potassium hydroxide = K+1 and OH-1 = KOH (aq) Lead (II) hydroxide = Pb+2 and OH-1 = Pb(OH)2 (aq)
Lead (IV) hydroxide = Pb+4 and OH-1 = Pb(OH)4 (aq)
Lithium hydroxide = Copper (II) hydroxide = Magnesium hydroxide =
Neutralization
(c) 2006, Mark Rosengarten
H+1 + OH-1 HOH Acid + Base Water + Salt (double replacement) HCl (aq) + NaOH (aq) HOH (l) + NaCl (aq) H2SO4 (aq) + KOH (aq) 2 HOH (l) + K2SO4 (aq) HBr (aq) + LiOH (aq) H2CrO4 (aq) + NaOH (aq) HNO3 (aq) + Ca(OH)2 (aq) H3PO4 (aq) + Mg(OH)2 (aq)
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pH
(c) 2006, Mark Rosengarten
A change of 1 in pH is a tenfold increase in acid or base strength.
A pH of 4 is 10 times more acidic than a pH of 5. A pH of 12 is 100 times more basic than a pH of 10.
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Indicators
(c) 2006, Mark Rosengarten
At a pH of 2:
Methyl Orange = red
Bromthymol Blue = yellow
Phenolphthalein = colorless
Litmus = red
Bromcresol Green = yellow
Thymol Blue = yellow
Methyl orange is red at a pH of 3.2 and below and yellow at a pH of 4.4 and higher. In between the two numbers, it is an intermediate color that is not listed on this table.
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Alternate Theories
(c) 2006, Mark Rosengarten
Arrhenius Theory: acids and bases must be in aqueous solution.
Alternate Theory: Not necessarily so! Acid: proton (H+1) donor…gives up H+1 in a reaction. Base: proton (H+1) acceptor…gains H+1 in a reaction.
HNO3 + H2O H3O+1 + NO3-1
Since HNO3 lost an H+1 during the reaction, it is an acid.
Since H2O gained the H+1 that HNO3 lost, it is a base.
Website-video
Oxidation and Reduction
(c) 2006, Mark Rosengarten
1) Oxidation Numbers2) Identifying OX, RD and SI Species3) Agents4) Writing Half-Reactions5) Balancing Half-Reactions6) Activity Series7) Voltaic Cells8) Electrolytic Cells9) Electroplating
Oxidation Numbers
(c) 2006, Mark Rosengarten
Elements have no charge until they bond to other elements. Na0, Li0, H2
0. S0, N20, C60
0
The formula of a compound is such that the charges of the elements making up the compound all add up to zero.
The symbol and charge of an element or polyatomic ion is called a SPECIES.
Determine the charge of each species in the following compounds:
NaCl KNO3 CuSO4 Fe2(CO3)3
Video
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Identifying OX, RD, SI Species
(c) 2006, Mark Rosengarten
Ca0 + 2 H+1Cl-1 Ca+2Cl-12 + H2
0
Oxidation = loss of electrons. The species becomes more positive in charge. For example, Ca0 Ca+2, so Ca0 is the species that is oxidized.
Reduction = gain of electrons. The species becomes more negative in charge. For example, H+1 H0, so the H+1 is the species that is reduced.
Spectator Ion = no change in charge. The species does not gain or lose any electrons. For example, Cl-1 Cl-1, so the Cl-1 is the spectator ion.
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Agents
(c) 2006, Mark Rosengarten
Ca0 + 2 H+1Cl-1 Ca+2Cl-12 + H2
0
Since Ca0 is being oxidized and H+1 is being reduced, the electrons must be going from the Ca0 to the H+1.
Since Ca0 would not lose electrons (be oxidized) if H+1 weren’t there to gain them, H+1 is the cause, or agent, of Ca0’s oxidation. H+1 is the oxidizing agent.
Since H+1 would not gain electrons (be reduced) if Ca0 weren’t there to lose them, Ca0 is the cause, or agent, of H+1’s reduction. Ca0 is the reducing agent.
Writing Half-Reactions
(c) 2006, Mark Rosengarten
Ca0 + 2 H+1Cl-1 Ca+2Cl-12 + H2
0
Oxidation: Ca0 Ca+2 + 2e- Reduction: 2H+1 + 2e- H2
0
The two electrons lost by Ca0 are gained by the two H+1 (each H+1 picks up an electron).
PRACTICE SOME!
Video
Practice Half-Reactions
(c) 2006, Mark Rosengarten
Don’t forget to determine the charge of each species first!
4 Li + O2 2 Li2O Oxidation Half-Reaction: Reduction Half-Reaction:
Zn + Na2SO4 ZnSO4 + 2 Na Oxidation Half-Reaction: Reduction Half-Reaction:
Balancing Half-Reactions
(c) 2006, Mark Rosengarten
Ca0 + Fe+3 Ca+2 + Fe0
Ca’s charge changes by 2, so double the Fe. Fe’s charge changes by 3, so triple the Ca.
3 Ca0 + 2 Fe+3 3 Ca+2 + 2 Fe0
Try these: __Na0 + __H+1 __Na+1 + __H2
0
(hint: balance the H and H2 first!)
__Al0 + __Cu+2 __Al+3 + __Cu0
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Activity Series
(c) 2006, Mark Rosengarten
For metals, the higher up the chart the element is, the more likely it is to be oxidized. This is because metals like to lose electrons, and the more active a metallic element is, the more easily it can lose them.
For nonmetals, the higher up the chart the element is, the more likely it is to be reduced. This is because nonmetals like to gain electrons, and the more active a nonmetallic element is, the more easily it can gain them.
Metal Activity
(c) 2006, Mark Rosengarten
Metallic elements start out with a charge of ZERO, so they can only be oxidized to form (+) ions.
The higher of two metals MUST undergo oxidation in the reaction, or no reaction will happen.
The reaction 3 K + FeCl3 3 KCl + Fe WILL happen, because K is being oxidized, and that is what Table J says should happen.
The reaction Fe + 3 KCl FeCl3 + 3 K will NOT happen.
3 K0 + Fe+3Cl-13
REACTION
Fe0 + 3 K+1Cl-1
NO REACTION
Voltaic Cells
(c) 2006, Mark Rosengarten
Produce electrical current using a spontaneous redox reaction
Used to make batteries! Materials needed: two beakers, piece of the oxidized
metal (anode, - electrode), solution of the oxidized metal, piece of the reduced metal (cathode, + electrode), solution of the reduced metal, porous material (salt bridge), solution of a salt that does not contain either metal in the reaction, wire and a load to make use of the generated current!
Use Reference Table J to determine the metals to use Higher = (-) anode Lower = (+) cathode
Animation
Animation
Making Voltaic Cells
(c) 2006, Mark Rosengarten
Create
Your
Own
Cell!!!!
More
Info!!!
How It Works
(c) 2006, Mark Rosengarten
The Zn0 anode loses 2 e-, which go up the wire and through the load. The Zn0 electrode gets smaller as the Zn0 becomes Zn+2 and dissolves into solution. The e- go into the Cu0, where they sit on the outside surface of the Cu0 cathode and wait for Cu+2 from the solution to come over so that the e- can jump on to the Cu+2 and reduce it to Cu0. The size of the Cu0 electrode increases. The negative ions in solution go over the salt bridge to the anode side to complete the circuit.
Since Zn is listed above Cu, Zn0 will be oxidized when it reacts with Cu+2. The reaction: Zn + CuSO4 ZnSO4 + Cu
You Start At The Anode
(c) 2006, Mark Rosengarten
Vital to make a batteryIs this electrochemistryYou take two half-cellsAnd connect them up so wellWith a load to power in between
You need to have electrodes you seeFull of that metallicityLet electrons flowAcross the salt bridge we go!Allowing us to make electricity
We start the anodeElectrons are lost thereAnd go through the wireAnd through the load on fireThey get to the cathodeAnd reduce the cationsAnd the anions go through the salt bridgeBack to where…WHERE?
Make Your Own Cell!!!
(c) 2006, Mark Rosengarten
Electrolytic Cells
(c) 2006, Mark Rosengarten
Use electricity to force a nonspontaneous redox reaction to take place.
Uses for Electrolytic Cells: Decomposition of Alkali Metal Compounds Decomposition of Water into Hydrogen and Oxyg
en Electroplating
Differences between Voltaic and Electrolytic Cells: ANODE: Voltaic (-)
Electrolytic (+) CATHODE: Voltaic (+) Electrolytic (-) Voltaic: 2 half-cells, a salt bridge and a load Electrolytic: 1 cell, no salt bridge, IS the load
Website & Video
Video
Decomposing AlkaliMetal Compounds
(c) 2006, Mark Rosengarten
2 NaCl 2 Na + Cl2
The Na+1 is reduced at the (-) cathode, picking up an e- from the battery
The Cl-1 is oxidized at the (+) anode, the e- being pulled off by the battery (DC)
Decomposing Water
(c) 2006, Mark Rosengarten
2 H2O 2 H2 + O2
The H+ is reduced at the (-) cathode, yielding H2 (g), which is trapped in the tube.
The O-2 is oxidized at the (+) anode, yielding O2 (g), which is trapped in the tube.
Electroplating
(c) 2006, Mark Rosengarten
The Ag0 is oxidized to Ag+1 when the (+) end of the battery strips its electrons off.
The Ag+1 migrates through the solution towards the (-) charged cathode (ring), where it picks up an electron from the battery and forms Ag0, which coats on to the ring.
Organic Chemistry
(c) 2006, Mark Rosengarten
1) Hydrocarbons
2) Substituted Hydrocarbons3) Organic Families4) Organic Reactions
Hydrocarbons
(c) 2006, Mark Rosengarten
Molecules made of Hydrogen and Carbon Carbon forms four bonds, hydrogen forms one bond Hydrocarbons come in three different homologous
series: Alkanes (single bond between C’s, saturated) Alkenes (1 double bond between 2 C’s, unsaturated) Alkynes (1 triple bond between 2 C’s, unsaturated)
These are called aliphatic, or open-chain, hydrocarbons.
Count the number of carbons and add the appropriate suffix! website
Alkanes
(c) 2006, Mark Rosengarten
CH4 = methane
C2H6 = ethane
C3H8 = propane
C4H10 = butane
C5H12 = pentane
To find the number of hydrogens, double the number of carbons and add 2.
website
Methane
(c) 2006, Mark Rosengarten
Meth-: one carbon
-ane: alkane
The simplest organic molecule, also known as natural gas!
Ethane
(c) 2006, Mark Rosengarten
Eth-: two carbons
-ane: alkane
Propane
(c) 2006, Mark Rosengarten
Prop-: three carbons
-ane: alkane
Also known as “cylinder gas”, usually stored under pressure and used for gas grills and stoves. It’s also very handy as a fuel for Bunsen burners!
Butane
(c) 2006, Mark Rosengarten
But-: four carbons
-ane: alkane
Liquefies with moderate pressure, useful for gas lighters. You have probably lit your gas grill with a grill lighter fueled with butane!
Pentane
(c) 2006, Mark Rosengarten
Pent-: five carbons
-ane: alkane
Your Turn!!!
Draw Hexane:
Draw Heptane:
Alkenes
(c) 2006, Mark Rosengarten
C2H4 = Ethene
C3H6 = Propene
C4H8 = Butene
C5H10 = Pentene
To find the number of hydrogens, double the number of carbons.
website
Ethene
(c) 2006, Mark Rosengarten
Two carbons, double bonded. Notice how each carbon has four bonds? Two to the other carbon and two to hydrogen atoms.
Also called “ethylene”, is used for the production of polyethylene, which is an extensively used plastic. Look for the “PE”, “HDPE” (#2 recycling) or “LDPE” (#4 recycling) on your plastic bags and containers!
Propene
(c) 2006, Mark Rosengarten
Three carbons, two of them double bonded. Notice how each carbon has four bonds?
If you flipped this molecule so that the double bond was on the right side of the molecule instead of the left, it would still be the same molecule. This is true of all alkenes.
Used to make polypropylene (PP, recycling #5), used for dishwasher safe containers and indoor/outdoor carpeting!
Butene
(c) 2006, Mark Rosengarten
This is 1-butene, because the double bond is between the 1st and 2nd carbon from the end. The number 1 represents the lowest numbered carbon the double bond is touching.
This is 2-butene. The double bond is between the 2nd and 3rd carbon from the end. Always count from the end the double bond is closest to.
ISOMERS: Molecules that share the same molecular formula, but have different structural formulas. Video
Pentene
(c) 2006, Mark Rosengarten
This is 1-pentene. The double bond is on the first carbon from the end.
This is 2-pentene. The double bond is on the second carbon from the end.
This is not another isomer of pentene. This is also 2-pentene, just that the double bond is closer to the right end.
Alkynes
(c) 2006, Mark Rosengarten
C2H2 = Ethyne
C3H4 = Propyne
C4H6 = Butyne
C5H8 = Pentyne
To find the number of hydrogens, double the number of carbons and subtract 2.
website
Ethyne
(c) 2006, Mark Rosengarten
Now, try to draw propyne! Any isomers? Let’s see!
Also known as “acetylene”, used by miners by dripping water on CaC2 to light up mining helmets. The “carbide lamps” were attached to miner’s helmets by a clip and had a large reflective mirror that magnified the acetylene flame.
Used for welding and cutting applications, as ethyne burns at temperatures over 3000oC!
Propyne
(c) 2006, Mark Rosengarten
This is propyne! Nope! No isomers.
OK, now draw butyne. If there are any isomers, draw them too.
Butyne
(c) 2006, Mark Rosengarten
Well, here’s 1-butyne!
And here’s 2-butyne!
Is there a 3-butyne? Nope! That would be 1-butyne. With four carbons, the double bond can only be between the 1st and 2nd carbon, or between the 2nd and 3rd carbons.
Now, try pentyne!
Pentyne
(c) 2006, Mark Rosengarten
1-pentyne
2-pentyne
Now, draw all of the possible isomers for hexyne!
Substituted Hydrocarbons
(c) 2006, Mark Rosengarten
Hydrocarbon chains can have three kinds of “dingly-danglies” attached to the chain. If the dingly-dangly is made of anything other than hydrogen and carbon, the molecule ceases to be a hydrocarbon and becomes another type of organic molecule. Alkyl groups Halide groups Other functional groups
To name a hydrocarbon with an attached group, determine which carbon (use lowest possible number value) the group is attached to. Use di- for 2 groups, tri- for three.
Alkyl Groups
(c) 2006, Mark Rosengarten
website
Halide Groups
(c) 2006, Mark Rosengarten
website
Organic Families
(c) 2006, Mark Rosengarten
Each family has a functional group to identify it. Alcohol (R-OH, hydroxyl group) Organic Acid (R-COOH, primary carboxyl group) Aldehyde (R-CHO, primary carbonyl group) Ketone (R1-CO-R2, secondary carbonyl group) Ether (R1-O-R2) Ester (R1-COO-R2, carboxyl group in the middle) Amine (R-NH2, amine group) Amide (R-CONH2, amide group)
These molecules are alkanes with functional groups attached. The name is based on the alkane name.
website
Video
Alcohol
(c) 2006, Mark Rosengarten
On to DI and TRIHYDROXY ALCOHOLS
Di and Tri-hydroxy Alcohols
(c) 2006, Mark Rosengarten
Positioning of Functional Group
(c) 2006, Mark Rosengarten
PRIMARY (1o): the functional group is bonded to a carbon that is on the end of the chain.
SECONDARY (2o): The functional group is bonded to a carbon in the middle of the chain.
TERTIARY (3o): The functional group is bonded to a carbon that is itself directly bonded to three other carbons.
Organic Acid
(c) 2006, Mark Rosengarten
These are weak acids. The H on the right side is the one that ionized in water to form H3O+. The -COOH (carboxyl) functional group is always on a PRIMARY carbon.
Can be formed from the oxidation of primary alcohols using a KMnO4 catalyst.
Aldehyde
(c) 2006, Mark Rosengarten
Aldehydes have the CO (carbonyl) groups ALWAYS on a PRIMARY carbon. This is the only structural difference between aldehydes and ketones.
Formed by the oxidation of primary alcohols with a catalyst. Propanal is formed from the oxidation of 1-propanol using pyridinium chlorochromate (PCC) catalyst.*
Ketone
(c) 2006, Mark Rosengarten
Ketones have the CO (carbonyl) groups ALWAYS on a SECONDARY carbon. This is the only structural difference between ketones and aldehydes.
Can be formed from the dehydration of secondary alcohols with a catalyst. Propanone is formed from the oxidation of 2-propanol using KMnO4 or PCC catalyst.*
Ether
(c) 2006, Mark Rosengarten
Ethers are made of two alkyl groups surrounding one oxygen atom. The ether is named for the alkyl groups on “ether” side of the oxygen. If a three-carbon alkyl group and a four-carbon alkyl group are on either side, the name would be propyl butyl ether.
Ester
(c) 2006, Mark Rosengarten
Esters are named for the alcohol and organic acid that reacted by esterification to form the ester. If the alcohol was 1-propanol and the acid was hexanoic acid, the name of the ester would be propyl hexanoate. Esters contain a COO (carboxyl) group in the middle of the molecule, which differentiates them from organic acids.
Amine
(c) 2006, Mark Rosengarten
- Component of amino acids, and therefore proteins, RNA and DNA…life itself!
- Essentially ammonia (NH3) with the hydrogens replaced by one or more hydrocarbon chains, hence the name “amine”!
Amide
(c) 2006, Mark Rosengarten
Synthetic Polyamides: nylon, kevlar
Natural Polyamide: silk!
For more information on polymers, go here.
Organic Reactions
(c) 2006, Mark Rosengarten
Combustion Fermentation Substitution Addition Dehydration Synthesis
Etherification Esterification
Saponification Polymerization
Combustion
(c) 2006, Mark Rosengarten
Happens when an organic molecule reacts with oxygen gas to form carbon dioxide and water vapor. Also known as “burning”.
Fermentation
(c) 2006, Mark Rosengarten
Process of making ethanol by having yeast digest simple sugars anaerobically. CO2 is a byproduct of this reaction.
The ethanol produced is toxic and it kills the yeast when the percent by volume of ethanol gets to 14%.
Substitution
(c) 2006, Mark Rosengarten
Alkane + Halogen Alkyl Halide + Hydrogen Halide The halogen atoms substitute for any of the hydrogen
atoms in the alkane. This happens one atom at a time. The halide generally replaces an H on the end of the molecule.
C2H6 + Cl2 C2H5Cl + HClThe second Cl can then substitute for another H:
C2H5Cl + HCl C2H4Cl2 + H2
Video
Addition
(c) 2006, Mark Rosengarten
Alkene + Halogen Alkyl Halide The double bond is broken, and the halogen adds at
either side of where the double bond was. One isomer possible.
Video
Etherification*
(c) 2006, Mark Rosengarten
Alcohol + Alcohol Ether + Water A dehydrating agent (H2SO4) removes H from one
alcohol’s OH and removes the OH from the other. The two molecules join where there H and OH were removed.
Note: dimethyl ether and diethyl ether are also produced from this reaction, but can be separated out.
Esterification
(c) 2006, Mark Rosengarten
Organic Acid + Alcohol Ester + Water A dehydrating agent (H2SO4) removes H from the organic
acid and removes the OH from the alcohol. The two molecules join where there H and OH were removed.
Saponification
(c) 2006, Mark Rosengarten
The process of making soap from glycerol esters (fats).
Glycerol ester + 3 NaOH soap + glycerol
Glyceryl stearate + 3 NaOH sodium stearate + glycerol
The sodium stearate is the soap! It emulsifies grease…surrounds globules with its nonpolar ends, creating micelles with - charge that water can then wash away. Hard water replaces Na+ with Ca+2 and/or other low solubility ions, which forms a precipitate called “soap scum”.
Water softeners remove these hardening ions from your tap water, allowing the soap to dissolve normally.
Polymerization
(c) 2006, Mark Rosengarten
A polymer is a very long-chain molecule made up of many monomers (unit molecules) joined together.
The polymer is named for the monomer that made it. Polystyrene is made of styrene monomer Polybutadiene is made of butadiene monomer
Addition Polymers Condensation Polymers Rubber
Addition Polymers
(c) 2006, Mark Rosengarten
Joining monomers together by breaking double bonds
Polyvinyl chloride (PVC): vinyl siding, PVC pipes, etc.
Vinyl chloride polyvinyl chloride
n C2H3Cl -(-C2H3Cl-)-n
Polytetrafluoroethene (PTFE, teflon):
TFE PTFE
n C2F4 -(-C2F4-)-n
Condensation Polymers
(c) 2006, Mark Rosengarten
Condensation polymerization is just dehydration synthesis, except instead of making one molecule of ether or ester, you make a monster molecule of polyether or polyester.
Rubber
(c) 2006, Mark Rosengarten
The process of toughing rubber by cross-linking the polymer strands with sulfur is called...
VULCANIZATION!!!
(c) 2006, Mark Rosengarten
Vocabulary
(c) 2006, Mark Rosengarten
(c) 2006, Mark Rosengarten
Nucleon – particle found in the nucleus of an atom – includes the proton and neutron only – equal to the mass number of an atomIsotope – atoms of the same element which have the same atomic number but different mass numberAtomic Number - equal to the number of protons in the nucleus of an atomMass Number - equal to the sum of the protons and neutrons in the nucleus of an atom.Nuclear charge - equal to the number of protons in the nucleus of an atom.Alpha Particle – A radioactive particle equivalent to a helium nucleus (2 protons, 2 neutrons) - Mass of 4 and a +2 chargeBeta Particle – A radioactive particle equivalent to an electron. Has no mass and -1 chargePositron – A radioactive particle equivalent to an positively charged electron. Has no mass and +1 chargeGamma Rays – High energy light given off during a nuclear process – Have no mass or chargeFission – A nuclear reaction where a large nucleus breaks up into smaller ones. This is what happens in nuclear power plantsFusion - process where two or more small nuclei combine to form a larger nucleus. Fusion is the reverse process of nuclear fission
(c) 2006, Mark Rosengarten
Valence Electron – Electrons in the outermost energy level (furthest away from the nucleus) – Generally the only electrons involved in chemical reactions.Electron Dot Diagram (EDD) – Symbol of an element surrounded by dots which represent valence elctronsStable Octet - The octet rule is a rule that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas.Bright Line Spectrum - When electrons jump from the excited state to the ground state, the electrons emit energy in the form of light, producing a bright-line spectrum. Each element has its own unique bright-line spectrum. Orbital- Regions of the most probable electron location in the wave-mechanical model of the atomSolid – phase of matter with a definite shape and volume and low entropy – particles arranged in a regular geometric pattern
(c) 2006, Mark Rosengarten
Liquid – phase of matter that has a definite volume but takes shape of its containerGas – phase of matter that takes the shape of & fills its entire container – has high entropy.Element - substances that are composed of atoms that have the same atomic number. Elements cannot be broken down by chemical change.Compound - substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means.Mixture - composed of two or more different substances that can be separated by physical means.When different substances are mixed together, a homogeneous or heterogeneous mixture is formed.Homogeneous Mixture – Components are evenly distributed – Also called solutions.Heterogeneous Mixture – Components are unevenly distributed
(c) 2006, Mark Rosengarten
Solution - a homogeneous mixture of a solute dissolved in a solventMelting – a phase change in which a solid changes to a liquidBoiling – the process of rapidly converting a liquid to its gaseous (vapor) state, typically by heating the liquid to a temperature called its boiling point.Boiling Point - temperature at which the vapor pressure is equal to the pressure of the gas above it.Freezing - a phase change in which a liquid cools and changes to a solidCondensation - a phase change in which a gas cools and changes to a liquidSublimation - When a solid can change directly into a gas skipping the liquid phaseEvaporation – a phase change in which a liquid changes to a gasExothermic – process which releases energy causing the temperature of its surroundings to increase
(c) 2006, Mark Rosengarten
Endothermic – process which absorbs energy causing the temperature of its surroundings to decreaseHeat of Fusion – Amount of heat in Joules or KF required to melt 1 gram of ice to waterHeat of Vaporization - Amount of heat in Joules or KF required to vaporize 1 gram of water to vaporMetals – Found on the left side of the Periodic table – Are malleable, ductile, lustrous, good conductors and form positive ionsMalleable – can be pounded into thin sheetsDuctile – can be stretched into wireLuster - shinyNonmetals – Found on the right side of the Periodic table – Are brittle, dull, poor conductors and form negative ionsMetalloids – have the properties of both metals and nonmetals – found along the stair-step lineIonization energy – amount of energy required to remove the most loosely held electron in an atom – Values found on table S
(c) 2006, Mark Rosengarten
Electronegativity – The attraction a nucleus has for electrons in a bond – Values found on Table S – Fluorine has highestAlkali metals – Group 1 metals - Most active metals, only found in compounds in nature – Form +1 ionsAlkaline Earth Metals – Group 2 metals - Very active metals, only found in compounds in nature – Form +2 ionsTransition Metals – Groups 3-11 - Many can form different possible charges of ions - Compounds containing these metals can be colored.Halogens – Group 17 nonmetals – Most reactive nonmetals – Fluorine most activeNoble Gases - Are completely nonreactive since they have eight valence electrons, making a stable octet.Diatomic Elements - Br2, I2, N2, Cl2, H2, O2 and F2
Ions - charged particles formed by the gain or loss of electrons.
(c) 2006, Mark Rosengarten
Positive Ion – Formed when an atom, usually a metal, loses 1 or more electronsNegative Ion – Formed when an atom, usually a nonmetal, gains 1 or more electrons.Ionic bond – bond that forms when a metal transfers valence electrons to a nonmetal. Covalent bond – bond that forms when nonmetals share valence electronsMetallic Bond – Bond that forms between metal atoms such as in copper wire – Described as “positve ions in a sea of mobile electrons”Ionic Compound - made of metal and nonmetal ions. Molecular Compound - made of nonmetal atoms bonded to form a distinct particle called a molecule. REDOX Reaction – Short for oxidation-reduction - driven by the loss (oxidation) and gain (reduction) of electrons.
(c) 2006, Mark Rosengarten
Oxidation – loss of electrons – oxidation number increasesReduction – gain of electrons – oxidation number decreasesPrecipitate – compound that forms as a result of a double replacement reaction which is insoluble in waterIntermolecular Attractive Forces(IMAF) – force of attraction between molecules such as hydrogen bonding, dipole-dipole, etc…Hydrogen Bond – A special type of dipole-dipole attraction that occurs when hydrogen is bonded to N, O or F.Gram Formula Mass - sum of atomic masses of all elements in the compound – equal to the mass of one mole of a compoundCatalyst – speeds up a chemical reaction by lowering the activation energy.Activation Energy – amount of energy needed to start a reactionHeat of Reaction(DH) – amount of heat absorbed or released during a chemical reaction
(c) 2006, Mark Rosengarten
Chemical Equilibrium – When the rate of the forward and reverse reactions are equalSolubility - the maximum quantity of solute that can be dissolved in a given quantity of solvent at a given temperatureArrhenius Acid - molecules that dissolve in water to produce H+ or H3O+ (hydronium) as the only positively charged ion in solution.Arrhenius Base - molecules that dissolve in water to produce OH- (hydroxide) as the only negatively charged ion in solution.Bronsted-Lowry Acid – proton (H+) donorBronsted-Lowry Base – proton (H+) acceptorVoltaic cell - Produce electrical current using a spontaneous redox reaction – used to make batteriesElectrolytic cell - Use electricity to force a nonspontaneous redox reaction to take place.Anode – electrode at which oxidation occursCathode – electrode at which reduction occurs
(c) 2006, Mark Rosengarten
Salt bridge – allows for the movement of ionsHydrocarbons - Molecules made of Hydrogen and CarbonAlkanes – saturated hydrocarbons with only single bonds between carbon atomsAlkenes – unsaturated hydrocarbons with at least one double bond between carbon atomsAlkynes – unsaturated hydrocarbons with at least one triple bond between carbon atomsEsterification - reaction between an alcohol and organic acid which produces an ester and waterFermentation – reaction of a sugar with an enzyme that produces alcohol and CO2
Polymerization – process of joining many small molecules(monomers) to make a large molecule(polymer).Saponification – A fat or oil reacts with a strong base and produces a soap
(c) 2006, Mark Rosengarten
Isomer – compounds that have the same chemical formula but different structures