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TRANSCRIPT
Introduction to Chemistry
Compiled from Various Sources:
Wikipedia, Regents Reference
Table, Text Books.
God created our natural world and
filled it with various different materials –
common and exotic.
God created mankind with intelligence
and curiosity about the world around
them.
Introduction
What are the natural things made of?
Why some things like metals conduct
electricity – whereas other materials
are non-conductors?
What makes them different?
Introduction
What makes metals like gold and
platinum stable for indefinite period of
time – whereas materials made of iron
rust?
This field of curiosity is about four
thousand years old.
Introduction
Chemistry Involves Studying the
Properties and Behavior of Matter.
Matter is the Physical Material of the
Universe; it is Anything that has Mass
and Occupies Space.
Matter and Chemistry
A Property is any Characteristic that
Allows us to Recognize a Particular
Type of Matter and to Distinguish it
from Other Types.
Matter and Chemistry
Chemistry Provides Important
Understanding of Our World and How it
Works.
It is an Extremely Practical Science that
Greatly Impacts our Daily Living.
Chemistry
Matters are made up of Basic
Building Blocks Called Elements.
An Element is a Pure Substance that
cannot be Separated into Simpler
Substances by Physical or Chemical
Means.
Matters
Matters are made up of Basic
Building Blocks Called Elements.
91 Such Elements Occur Naturally on
Earth.
Copper, Oxygen, and Gold – Examples.
Each Element has a Unique Chemical
Name and Symbol.
Matters
Element Proportion (by mass)
Oxygen 65%
Carbon 18%
Hydrogen 10%
Nitrogen 3%
Calcium 1.5%
Phosphorus 1.2%
Potassium 0.2%
Sulfur 0.2%
Chlorine 0.2%
Sodium 0.1%
Magnesium 0.05%
Iron < 0.05%
Cobalt < 0.05%
Copper < 0.05%
Zinc < 0.05%
Iodine < 0.05%
Selenium < 0.01%
Three Main Classifications:
1. Metals: Generally Shiny when
Smooth and Clean, Solid at RT, and
Good Conductors of Heat and
Electricity.
Elements
2. Nonmetals: Generally Gases or
Brittle – Dull-looking Solids. Poor
Conductors of Heat and Electricity.
The only Nonmetal that is Liquid at
RT is Bromine.
Elements
3. Metalloids: Physical and Chemical
Properties of Both Metals and
Nonmetals.
B, Si, Ge, As, Sb, Te, Po, and At are Eight
Metalloids.
Elements
Elements are made up of
1. A heavy small nucleus –
containing protons and
neutrons;
2. Light electrons spinning
around the nucleus.
Elements
Protons are Positively
Charged.
Electrons are Negatively
Charged.
Elements
Are Arranged in the Periodic table
in the Ascending Order of the
Number of Protons.
An Element is Characterized by its
Number of Protons – Atomic
Number.
Elements
Except Some Metals and the Group
18 Elements (Inert Gases) – the
Elements themselves are too
Unstable to be Found Alone in
Nature.
Molecules or Compounds
They Combine with the Same or
Different Element(s) to Make More
Stable Molecules or Compounds.
Molecules or Compounds
A Compound is a Combination of
Two or More Different Elements
that are Combined Chemically.
Compounds
Are Formed When Metals Combine
with Nonmetals.
LiF Li + F -
LiCl Li + Cl -
KF K + F -
Ionic Compounds
LiF Li + F -
Li + has 3 Protons and 2 Electrons,
F – has 9 Protons and 10 Electrons.
Cl – has 17 Protons and 18 Electrons.
K + has 19 Protons and 18 Electrons.
Ionic Compounds
Are Formed When Nonmetals
Combine with Nonmetals.
Molecular Compounds or Molecules.
H2O, NH3, CH4
Covalent Compounds
The Smallest Particle of an Element
that Retains the Properties of the
Element is Called an Atom.
Atoms
The smallest atom is helium with a radius of 32 pm,
while one of the largest is cesium at 225 pm.
A picometer (symbol pm) is a unit of length in the
metric system, equal to one trillionth, i.e.
(1/1,000,000,000,000) of a meter. It can be written in
scientific notation as 1×10−12 m (scientific notation) or
1 E−12 m (engineering notation) — both meaning 1
m / 1,000,000,000,000.
width of a strand of human hair is 10-4 meters or 100
µm.
Atoms
Some examples will demonstrate the minuteness of the atom.
width of a strand of human hair is 10-4 meters or 100 µm
A typical human hair is about 1 million carbon atoms in width.
A single drop of water contains about 2 sextillion (2 × 1021) atoms
of oxygen, and twice the number of hydrogen atoms.
A single carat diamond with a mass of 2 × 10-4 kg contains about
10 sextillion (1022) atoms of carbon.
If an apple were magnified to the size of the Earth, then the
atoms in the apple would be approximately the size of the original
apple.
Atoms
A Molecule is Formed when Two or
More Atoms Bond Covalently.
Molecules
H2, O2, N2, F2, Cl2, Br2,and I2 – These
are not Compounds – Composed of a
Single Element.
H2O, CO2, CH4 – are Compounds –
Each is Made from More than One
Element.
Molecules/Compounds
All Atoms are Neutral – Number of
Protons and the Number of electrons in
an Atom must be Equal.
Atomic Number = Number of Protons
= Number of
Electrons
Number of Electrons
All atoms of a Particular Element have
the Same Number of Protons and
Electrons – the Number of Neutrons on
their Nuclei May Differ.
Three Types of Carbon Atoms: 6
Neutrons, 7 Neutrons, and 8 Neutrons.
Isotopes
Atoms - with the same number of
Protons and Electrons but Different
Number of Neutrons – are Called
Isotopes.
Isotopes have different masses, but
essentially the same Chemical
Behavior – determined by the number
of Electrons.
Isotopes
To Make it Easy to Identify each of the
Various Isotopes of an Element,
Chemists Add a Number after the
Elements Name (C-14).
This Number is Called the Mass
Number – Represents the Sum of the
Number of Protons and Neutrons.
Isotopes
107Ag 109 Ag
47 47
Number of Neutrons = Mass
Number – Atomic Number
Isotopes
The Arrangement of electrons in an Atom is
called the Atom’s Electron Configuration.
(Ions Electron Configuration)
The Most Stable, Lowest-Energy
Arrangement of the Electrons in an Atom is
Called its Ground-State Electron
Configuration.
Electron Configuration
The Periodic Table found in your Reference
Table Gives you these Ground-State
Electron Configuration for each Element
underneath the Symbol of the Element.
Electron Configuration
Only Certain Electrons – Valence
Electrons – Determine the Chemical
Properties of an element.
Valence Electrons
Electrons in the Outermost Orbitals
(the Last Number on your Ref. Tab.
Periodic table underneath the symbol
of the Element).
C 2-4 4 is the # of V. Electrons.
Valence Electrons
Because the Valence Electrons are
Involved in Forming Chemical Bonds
– Chemists often Represent them
Visually using a Simple Shorthand
Method.
Electron-Dot Structure
Consists of the Element Symbol –
which Represents the Atomic Nucleus
and Inner Electrons – Surrounded by
Dots Representing the Atom’s
Valence Electrons.
Electron-Dot Structure
An American Chemist G.N. Lewis
(1875-1946) Devised this method
while teaching a College Chemistry
Class in 1902 – Lewis Dot structures.
Electron-Dot Structure
Dots – Representing Valence
Electrons – are Placed one at a time
on the four sides of the symbol (any
sequence is ok) and then paired up
until all are used.
Electron-Dot Structure
The Atoms tend to Gain, Lose, or
Share Electrons in order to acquire a
full set of eight valence electrons.
Exceptions: H, He, Li, Be, B
Octet Rule
The Force that Holds Two Atoms
Together is Called A Chemical Bond.
Attraction between a Positive Nucleus and
Negative Electrons.
Attraction between a Positive Ion and a
Negative Ion.
Chemical Bonds
When the Elements Sodium and
Chlorine Reacts – a Sodium atom
transfers its valence electron to a
Chlorine atom – becomes a Positive
Ion. The Chlorine atom accepts this
electron - becomes a Negative Ion.
Ionic Bonds
Metals usually Lose electrons to form
Positive Ions – Cations.
Nonmetals usually Gain electrons to
form Negative Ions – Anions.
Ions
The main principle to remember is that
ions are completely different in
physical and chemical properties from
the neutral atoms of the element .
Ions
Whereas elements are neutral in charge,
IONS have either a positive or negative
charge depending upon whether there is
an excess of protons (positive ion) or
excess of electrons (negative ion).
Ions
The Compound Sodium Chloride
forms because of the Attraction
between Oppositely charged Na+ and
Cl- Ions.
Ionic Bonds
The Electrostatic Force that Holds
Oppositely Charged Particles Together
in an Ionic Compound is Referred to as
Ionic Bond.
Compounds that Contain Ionic Bonds are
Ionic Compounds.
Ionic Bonds
Ionic Compounds Contain Both
Cations and Anions.
The Simplest Ratio of the Ions
Represented in an Ionic Compound is
Called a Formula Unit.
Formulas – Ionic Compounds
Because the Total Number of Electrons
Gained by the Nonmetallic Atoms must
Equal the Total Number of Electrons
Lost by the Metallic Atoms – the
Overall Charge of the Formula Unit is
Zero.
Formulas – Ionic Compounds
Na+Cl-, K+Cl-, Li+Cl-
NaCl, KCl, LiCl
Mg2+O2-, Mg2+2Cl-, 2Na+O2-
MgO, MgCl2, Na2O
Al3+3Cl-
AlCl3
Ionic Compounds
Mg2+ F- F-
MgF2
Ions Made up of More than One Atom. The
Charge Applies to the Entire Group Of
Atoms.
NH4+
PO43-
Just Treat them as a Single Atom. Do Not
Separate the Atoms.
Polyatomic Ions
Na+ and PO43- Na3 PO4
Ca2+ and PO43- Ca3 (PO4
)2
Ca2+ PO43-
Number 1 is never written – Just
Understood.
Formula Units
Sodium Chloride
Calcium Carbonate
Ammonium Nitrate
First the Name of the Cation – then the Name
of the Anion – Ending Changed for some
Anions from Single Atoms.
Naming – Ionic Compounds
Naming – Ionic Compounds
Atom Name Ion Name
Chlorine Chloride
Fluorine Fluoride
Bromine Bromide
Iodine Iodide
Oxygen Oxide
Sulfur Sulfide
Nitrogen Nitride
Phosphorus Phosphide
Selenium Selenide
Hydrogen Hydride
Na2 S
CaO
K I
NaH
Na3P
Li3N
Naming – Ionic Compounds
Na2 S Sodium Sulfide
CaO Calcium Oxide
K I Potassium Iodide
NaH Sodium Hydride
Na3P Sodium Phosphide
Li3N Lithium Nitride
Naming – Ionic Compounds
Na2S2O3 Sodium Thiosulfate
CaSO4 Calcium Sulfate
K2CrO4 Potassium Chromate
NaClO Sodium Hypochlorite
(NH4)2SO4 Ammonium Sulfate
LiClO4 Lithium Perchlorate
Naming – Ionic Compounds
All Ionic compounds tend to have the
following characteristics:
1. Usually solid at room temperature
forming a crystal lattice structure.
Properties Of Ionic Compounds
2. Most ionic compounds are brittle and
break under stress.
3. Usually soluble in water, the polar
water molecule pulls the cations and
anions apart to cause dissociation.
Properties Of Ionic Compounds
4. Ionic compounds conduct electricity
when dissociated or molten.
5. Usually have very high melting points
(unlike covalent compounds).
Sodium chloride, NaCl, melts at 8010C
Properties Of Ionic Compounds
Many of the Ionic Compounds are Soluble
in Water.
Solubility – Temp Relationships of a few
Solid Ionic Compounds are Shown in
Table G in the Reference Table.
(KI, NaNO3, KNO3, NH4Cl, KCl, NaCl,
and KClO3.
Properties Of Ionic Compounds
But there are some Ionic Compounds
which are considered Insoluble in water.
Table F – Reference Table has that
Information.
Properties Of Ionic Compounds
The Atoms tend to Gain, Lose, or Share
Electrons in order to acquire a full set of
eight valence electrons.
Exceptions: H, He, Li, Be, B
Review: Octet Rule
When Metals and Nonmetals react to
form binary Ionic Compounds –
Electrons are Transferred – Resulting
Ions have Noble-Gas (Inert Gas)
Electron Configurations.
Ionic Bond
But Sometimes Two Atoms that both
Need to Gain Valence Electrons to
become Stable – Can Share Electrons.
The Chemical Bond that Results from
the Sharing of the Valence Electrons is
a Covalent Bond.
Covalent Bond
But Sometimes Two Atoms that both
Need to Gain Valence Electrons to
become Stable – Can Share Electrons.
The Chemical Bond that Results from
the Sharing of the Valence Electrons is
a Covalent Bond.
Covalent Bond
But Sometimes Two Atoms that both
Need to Gain Valence Electrons to
become Stable – Can Share Electrons.
The Chemical Bond that Results from
the Sharing of the Valence Electrons is
a Covalent Bond.
Covalent Compounds
LecturePLUS Timberlake 91
Covalent Bonds
Formed between two nonmetals in 14,
15, 16, 17, and Hydrogen.
Electrons are shared
single bond shares one pair electrons
double bond shares two pairs
electrons
triple bond shares three pairs
electrons
LecturePLUS Timberlake 92
Covalent Bonds
Two nonmetal atoms form a covalent bond
because they have less energy after they
bonded
H + H H : H = HH = H2
hydrogen molecule
LecturePLUS Timberlake 93
Example
octets
N + N N:::N
triple bond
LecturePLUS Timberlake 94
Diatomic Molecules
Gases that exist as diatomic molecules
are H2, F2, N2, O2, Cl2, Br2, and I2
LecturePLUS Timberlake 95
Covalent Bonds in NH3
Bonding pairs
H
H : N : H
Lone pair of electrons
96
Naming Binary Covalent
Compounds
Two nonmetals
Name each element
End the last element in -ide
Add prefixes to show more than 1 atom
Prefixes
mono 1 penta 5
di 2 hexa 6
tri 3
tetra 4
Rules
1. The first element is named first, using
the elements name.
2. Second element is named as an Anion
(suffix "-ide")
3. Prefixes are used to denote the number
of atoms
4. "Mono" is not used to name the first
element
Note: when the addition of the Greek prefix
places two vowels adjacent to one another, the
"a" (or the "o") at the end of the Greek prefix is
usually dropped; e.g., "nonaoxide" would be
written as "nonoxide", and "monooxide" would
be written as "monoxide". The "i" at the end of
the prefixes "di-" and "tri-" are never dropped.
Prefix number
indicated
mono- 1
di- 2
tri- 3
tetra- 4
penta- 5
hexa- 6
hepta- 7
octa- 8
nona- 9
deca- 10
LecturePLUS Timberlake 98
Learning Check
Fill in the blanks to complete the following
names of covalent compounds.
CO carbon ______oxide
CO2 carbon _______________
PCl3 phosphorus _______chloride
CCl4 carbon ________chloride
N2O _____nitrogen _____oxide
LecturePLUS Timberlake 99
Solution
CO carbon monoxide
CO2 carbon dioxide
PCl3 phosphorus trichloride
CCl4 carbon tetrachloride
N2O dinitrogen monoxide
LecturePLUS Timberlake 100
Learning Check
A. P2O5 1) phosphorus oxide
2) phosphorus pentoxide
3) diphosphorus pentoxide
B. Cl2O7 1) dichlorine heptoxide 2) dichlorine oxide
3) chlorine heptoxide
C. Cl2 1) chlorine
2) dichlorine
3) dichloride
LecturePLUS Timberlake 101
Solution
A. P2O5 3) diphosphorus pentoxide
B. Cl2O7 1) dichlorine heptoxide
C. Cl2 1) chlorine
Formula Names
N2F6
CO2
SiF4
CBr4
NCl3
P2S3
CO
NO2
SF2
PF5
SO2
NO
CCl4
P2O5
Formula Names
N2F6 Dinitrogen Hexafluoride
CO2 Carbon Dioxide
SiF4 Silicon Tetrafluoride
CBr4 Carbon Tetrabromide
NCl3 Nitrogen Trichloride
P2S3 Diphosphorous Trisulfide
CO Carbon Monoxide
NO2 Nitrogen Dioxide
SF2 Sulfur Difluoride
PF5 Phosphorous Pentafluoride
SO2 Sulfur Dioxide
NO Nitrogen Monoxide
CCl4 carbon tetrachloride
P2O5 Diphosphorus pentoxide
104
Electronegativity
The attraction of an atom for electrons is
called its electronegativity.
Fluorine has the greatest
electronegativity.
The metals have low electronegativities.
Relative Scale (Reference Table: Pages
10-11) – no values are given for the inert gases
(Group 18 elements) because they do not bond
readily to other atoms.
105
Electronegativity:
• The ability of atoms in
a molecule to attract
electrons to itself.
• On the periodic chart,
electronegativity
increases as you go…
– …from left to right
across a row.
– …from the bottom to
the top of a column.
106
Figure 12.3: Electronegativity values for selected elements.
107
Table 12.1
108
Figure 12.4: The
three possible
types of bonds.
109
Figure 12.1: The formation of a bond between two atoms.
110
Figure 12.2: Probability representations of the electron
sharing in HF.
111
Bond Polarity: Nonpolar
Nonpolar covalent bond:
Electrons are shared between atoms
with the same electronegativity
values.
Difference = 0
Examples: N2 Br2
112
Bond Polarity: Polar
Polar covalent bond:
Electrons are shared between
different nonmetal atoms
Examples:
O-Cl O-S N-Cl
113
Bond Polarity: Ionic
Ionic bond:
Electrons are transferred between metal
and nonmetal atoms
NaCl KF
114
Learning Check
Identify the type of bond between the following atoms
A. K-N
1) nonpolar 2) polar 3) ionic
B. N-O
1) nonpolar 2) polar 3) ionic
C. Cl-Cl
1) nonpolar 2) polar 3) ionic
115
Solution
A. K-N 3) ionic
B. N-O 2) polar
C. Cl-Cl 1) nonpolar