ChemistryChemistry

Midterm ReviewMidterm Review

Describing MatterDescribing Matter

MassMass- an object is a - an object is a measure of the measure of the amount of matter amount of matter the object the object contains.contains.

VolumeVolume- is a - is a measure of the measure of the space occupied by space occupied by the object.the object.

PropertiesProperties

Physical Property-Physical Property- is a quality or is a quality or condition of a condition of a substance that can substance that can be observed or be observed or measured measured withoutwithout changing the changing the substance’s substance’s compositioncomposition

Boiling Point

Melting Point

Solid, Liquid, Gas

PropertiesProperties

Chemical Properties-Chemical Properties- ability of a substance ability of a substance to undergo a specific to undergo a specific chemical changechemical change

Words such as Words such as burn, burn, rot, rust, decompose, rot, rust, decompose, ferment, explode, ferment, explode, and corrodeand corrode usually usually indicate a chemical indicate a chemical change.change.

ChangesChanges

Physical Change-Physical Change- Some properties of Some properties of a material change, a material change, but the but the composition of the composition of the material does not material does not changechange

Cutting

Boiling

ChangesChanges

Chemical Chemical Change/Reaction-Change/Reaction- a a change in which change in which one or more one or more substances change substances change into one or more into one or more newnew substances. substances.

Fermentation

Burning

Chemical ReactionsChemical Reactions

ReactantReactant-a -a substance present at substance present at the start of the the start of the reaction.reaction.

ProductProduct-a substance -a substance produced in the produced in the reactionreaction

PrecipitatePrecipitate-a solid -a solid that forms and that forms and settles out of a liquid settles out of a liquid mixturemixture

Law of Conservation of Law of Conservation of Mass/MatterMass/Matter

During any During any chemical reaction, chemical reaction, the mass of the the mass of the products is always products is always equal to the mass equal to the mass of the reactants.of the reactants.

States that in any States that in any PHYSICAL or PHYSICAL or CHEMICAL change, CHEMICAL change, mass is conserved.mass is conserved.

Distinguishing MatterDistinguishing Matter

Matter

Elements CompoundsHeterogenous

MixturesHomogeneous

Mixtures

Substances

Mixtures

SubstancesSubstances ElementsElements- are the - are the

simplest form of matter simplest form of matter that has a unique set of that has a unique set of properties.properties.

CompoundsCompounds- are - are substances that contain substances that contain two or more elements two or more elements chemically combined in chemically combined in a fixed proportion; can a fixed proportion; can be broken down by be broken down by chemical meanschemical means

Elements and CompoundsElements and Compounds

Chemists use Chemists use symbolssymbols to to represent represent elements.elements.

Chemists use Chemists use chemical formulaschemical formulas to represent to represent compounds.compounds.

MixturesMixtures

Heterogeneous Heterogeneous Mixture-Mixture- a mixture a mixture in which the in which the composition is composition is NOTNOT uniform throughout.uniform throughout.

Homogeneous Homogeneous Mixture/Solution-Mixture/Solution- a a mixture in which mixture in which the composition the composition ISIS uniform throughout.uniform throughout.

Separating MixturesSeparating Mixtures

FiltrationFiltration- the process - the process that separates a solid that separates a solid from a liquid in a from a liquid in a heterogeneous heterogeneous mixture.mixture.

DistillationDistillation-when a -when a solution is boiled to solution is boiled to produce a vapor that produce a vapor that is then condensed in is then condensed in to a liquid; separates a to a liquid; separates a homogeneous homogeneous mixture.mixture.

Measurement and DensityMeasurement and Density

Density- mass per unit Density- mass per unit volume.volume.

D= m D= m ÷ v÷ v Units for density are Units for density are

g/ml or g/cmg/ml or g/cm33

Example- What is the Example- What is the density of an object density of an object which has a mass of which has a mass of 3.4 grams and a 3.4 grams and a volume of 45 mL?volume of 45 mL?

Answer: 0.076 g/mLAnswer: 0.076 g/mL

Kelvin ScaleKelvin Scale

To convert from To convert from Celsius to Kelvin, Celsius to Kelvin, simply add 273.simply add 273.

K = K = ˚C + 273˚C + 273 To convert to To convert to

Celsius from Celsius from Kelvin, simply Kelvin, simply subtract 273.subtract 273.

˚C = K - 273˚C = K - 273

Significant DigitsSignificant Digits

All nonzero digits ARE significant.All nonzero digits ARE significant.

Example: 1.234 (4)Example: 1.234 (4) All ZEROs to the right of the decimal point All ZEROs to the right of the decimal point

and at the end of the number ARE and at the end of the number ARE significant. significant.

Example: 4.00 (3)Example: 4.00 (3) All ZEROs used as place holders are NOT All ZEROs used as place holders are NOT

significant.significant.

Example: 2,000 (1) ; 0.00004 (1)Example: 2,000 (1) ; 0.00004 (1)

Add, Subtract, Multiply and Add, Subtract, Multiply and Divide with Significant DigitsDivide with Significant Digits

When adding or subtracting, the When adding or subtracting, the answer can have no more digits to the answer can have no more digits to the right of the decimal point than the one right of the decimal point than the one with the least.with the least.

Example: 2.03 + 1.3 = 3.33 = Example: 2.03 + 1.3 = 3.33 = 3.33.3 When multiplying and dividing, the When multiplying and dividing, the

answer can have no more SIG DIGS answer can have no more SIG DIGS than the one with the least.than the one with the least.

Example: 4.5 x 4 = 18 = Example: 4.5 x 4 = 18 = 2020

Atomic TheoryAtomic Theory

An An atomatom is the is the smallest particle of smallest particle of an element that an element that still retains those still retains those properties of that properties of that element.element.

History of the AtomHistory of the Atom

DemocritusDemocritus- Greek - Greek who believed that who believed that atoms were atoms were indivisible and indivisible and indestructible.indestructible.

John Dalton-John Dalton- English Chemist English Chemist that transformed that transformed Democritus’s ideas Democritus’s ideas into a theory. into a theory.

John Dalton’s Atomic TheoryJohn Dalton’s Atomic Theory

All elements are All elements are composed of tiny composed of tiny indivisible particles indivisible particles called atoms.called atoms.

Atoms of different Atoms of different elements can elements can physically mix physically mix together or can together or can chemically combine in chemically combine in simple whole-number simple whole-number ratios to form ratios to form compounds.compounds.

Atoms of the same Atoms of the same elements are identical.elements are identical.

Chemical reactions Chemical reactions occur when atoms are occur when atoms are separated, joined, or separated, joined, or rearranged. Atoms of rearranged. Atoms of one element, one element, however, are never however, are never changed into atoms of changed into atoms of another element as a another element as a result of a chemical result of a chemical reaction.reaction.

History of the AtomHistory of the Atom

J.J. Thomson- J.J. Thomson- English physicist English physicist that discovered the that discovered the electronelectron..

James Chadwick- James Chadwick- English physicist English physicist that discovered the that discovered the neutronneutron..

J.J. Thomson’s Cathode Ray J.J. Thomson’s Cathode Ray TubeTube

Thomson passed an Thomson passed an electric current electric current through gases at low through gases at low pressures sealed in a pressures sealed in a glass tube. glass tube.

AnodeAnode- positive - positive electrode; electrode; CathodeCathode- - negative electrode.negative electrode.

Glowing beam was Glowing beam was called the called the cathode cathode rayray, b/c it was , b/c it was negative.negative.

Ernest RutherfordErnest Rutherford

Rutherford pass Rutherford pass positive particles positive particles through a thin through a thin piece of gold foil.piece of gold foil.

Discovered the Discovered the protonproton..

Discovered that Discovered that the atom is mostly the atom is mostly empty space with a empty space with a positive center positive center called a called a nucleusnucleus..

Plum Pudding Model

Rutherford’s Model

The Modern AtomThe Modern Atom Electrons are located in the Electrons are located in the

electron cloud outside the electron cloud outside the nucleus.nucleus.

The nucleus is in the The nucleus is in the center and contains both center and contains both protons and neutrons.protons and neutrons.

Electrons are negative and Electrons are negative and have a mass of 1/1840 have a mass of 1/1840 amu.amu.

Protons are positive and Protons are positive and have a mass of 1 amu.have a mass of 1 amu.

Neutrons are neutral and Neutrons are neutral and have a mass of 1 amu.have a mass of 1 amu.

Amu stands for atomic Amu stands for atomic mass unit.mass unit.

Subatomic ParticlesSubatomic Particles

ProtonsProtons are equal to the are equal to the atomic atomic numbernumber..

ProtonsProtons are equal to the are equal to the electronselectrons if if there is no charge.there is no charge.

NeutronsNeutrons are equal to the are equal to the mass mass number – number of protons.number – number of protons.

Fill in the BlanksFill in the Blanks

SymbolsSymbols Atomic Atomic NumberNumber

ProtonsProtons NeutronsNeutrons Mass Mass NumberNumber

ElectronsElectrons

HH 11

1010 1010

77 1414

AnswersAnswers

SymbolsSymbols Atomic Atomic NumberNumber

ProtonsProtons NeutronsNeutrons Mass Mass NumberNumber

ElectronsElectrons

HH 11 11 00 11 11

NeNe 1010 1010 1010 2020 1010

NN 77 77 77 1414 77

IsotopesIsotopes

IsotopesIsotopes are atoms of the same are atoms of the same element with different numbers of element with different numbers of neutrons.neutrons.

Example- How many protons, Example- How many protons, neutrons, and electrons are in neon-neutrons, and electrons are in neon-20, neon-21, and neon-22?20, neon-21, and neon-22?

Answer- Neon-20, 10p, 10e, 10n; Answer- Neon-20, 10p, 10e, 10n; Neon-21, 10p, 10e, 11 n; Neon-22, Neon-21, 10p, 10e, 11 n; Neon-22, 10p, 10e, 12n.10p, 10e, 12n.

Periodic TablePeriodic Table J.W. Dobereiner- J.W. Dobereiner-

sorted the elements sorted the elements into groups called into groups called triadstriads..

The Law Of TriadsThe Law Of Triads -- -- Nature contains triads Nature contains triads of elements where the of elements where the middle element has middle element has properties that are an properties that are an average of the other average of the other two members of the two members of the triad when ordered by triad when ordered by the atomic weightthe atomic weight..

Periodic TablePeriodic Table

Dmitri Mendeleev- Dmitri Mendeleev- Russian chemist Russian chemist that arranged the that arranged the elements in his elements in his period table in period table in order of increasing order of increasing atomic mass.atomic mass.

Periodic LawPeriodic Law

In the modern In the modern periodic table, periodic table, elements are elements are arranged according arranged according to increasing to increasing atomic number.atomic number.

Henry Mosely first Henry Mosely first arranged the arranged the periodic table this periodic table this way.way.

MetalsMetals

Metals are good Metals are good conductors of heat and conductors of heat and electric current.electric current.

Have luster and sheen.Have luster and sheen. Solids at room Solids at room

temperature.temperature. Are ductile, able to be Are ductile, able to be

drawn into wires.drawn into wires. Are malleable- can be Are malleable- can be

hammered into flat hammered into flat sheets.sheets.

NonmetalsNonmetals

Poor conductors of Poor conductors of electricity and electricity and heat.heat.

Solid nonmetals Solid nonmetals tend to be brittle- tend to be brittle- break easily.break easily.

Mostly gases at Mostly gases at room temperature.room temperature.

Tend to be dull Tend to be dull instead of shiny.instead of shiny.

Carbon

Iodine

Metalloids/Semi-MetalsMetalloids/Semi-Metals

Generally have Generally have properties that are properties that are similar to those of similar to those of metals and metals and nonmetals.nonmetals.

Behave differently Behave differently under different under different conditions.conditions.

Silicon

Element BlocksElement Blocks

Show the symbol, Show the symbol, the name of the the name of the element, the element, the atomic number, atomic number, and the atomic and the atomic mass.mass.

Periodic Trends: Atomic Periodic Trends: Atomic RadiusRadius

Atomic Radius-Atomic Radius- one half the one half the distance between the nuclei of two distance between the nuclei of two atoms of the same element when the atoms of the same element when the atoms are joined.atoms are joined.

Atomic radius Atomic radius increases increases within a within a group b/c of the shielding effect and group b/c of the shielding effect and decreasesdecreases across a period due to across a period due to nuclear charge.nuclear charge.

Periodic Trends: Ionic Periodic Trends: Ionic RadiusRadius

Cations (positive ions) are always Cations (positive ions) are always smaller than the atoms from which smaller than the atoms from which they form.they form.

Anions (negative ions) are always Anions (negative ions) are always larger than the atoms from which larger than the atoms from which they form.they form.

Covalent Bonds vs. Ionic Covalent Bonds vs. Ionic BondsBonds

Covalent BondsCovalent Bonds A bond forms in which A bond forms in which

electrons are shared.electrons are shared. Can have single, Can have single,

double, or triple bonds.double, or triple bonds.

Ionic BondsIonic Bonds A bond forms in which A bond forms in which

electrons are electrons are transferred.transferred.

Only single bonds form.Only single bonds form.

Naming Ionic CompoundsNaming Ionic Compounds Name the metal first, and Name the metal first, and

the nonmetal second the nonmetal second replacing the ending with –replacing the ending with –ide.ide.

Example: NaExample: Na22O O Answer: Sodium OxideAnswer: Sodium Oxide

With Polyatomic IonsWith Polyatomic Ions Name them the same way Name them the same way

as before except where as before except where there is a polyatomic ion, there is a polyatomic ion, name it instead. NO name it instead. NO ENDINGS CHANGE!!! ENDINGS CHANGE!!!

Example: LiExample: Li33POPO44

Answer: Lithium phospate Answer: Lithium phospate

WITH TRANSITION METALSWITH TRANSITION METALS Name the metal first, and Name the metal first, and

the nonmetal second the nonmetal second replacing the ending with –replacing the ending with –ide.ide.

Use a roman numeral to Use a roman numeral to indicate the charge of the indicate the charge of the metal.metal.

Example: FeExample: Fe22OO33

Answer: Iron (III) oxideAnswer: Iron (III) oxide Example: CuOExample: CuO Answer: Copper (II) oxideAnswer: Copper (II) oxide

Naming Covalent Naming Covalent CompoundsCompounds

Name the first nonmetal first.Name the first nonmetal first. Name the second nonmetal second Name the second nonmetal second

replacing the ending with –ide.replacing the ending with –ide. Go back and use prefixes to indicate the Go back and use prefixes to indicate the

number of each nonmetal.number of each nonmetal. Example- CClExample- CCl4,4,, C, C22OO Answer: carbon tetrachloride, dicarbon Answer: carbon tetrachloride, dicarbon

monoxide.monoxide. Note: Make sure that if 2 vowels occur Note: Make sure that if 2 vowels occur

together, drop the first one. Never use together, drop the first one. Never use mono on the first nonmetal.mono on the first nonmetal.

Writing FormulasWriting Formulas

Write the symbol of the cation and Write the symbol of the cation and then the anion. Add whatever then the anion. Add whatever subscripts are needed to balance the subscripts are needed to balance the charges. (Criss-cross the charges.)charges. (Criss-cross the charges.)

Example- magnesium phosphideExample- magnesium phosphide MgMg+2+2 P P-3-3

Answer: MgAnswer: Mg33PP22

GOOD LUCK!!!!GOOD LUCK!!!!

Make sure to get plenty of rest.Make sure to get plenty of rest. Make sure to eat a good breakfast.Make sure to eat a good breakfast. Make sure to bring two #2 pencils Make sure to bring two #2 pencils

WITH erasers.WITH erasers.

STUDY, STUDY, STUDY!!!!STUDY, STUDY, STUDY!!!!