CHEMICAL BONDING
Text Book Chapters 7, 8, 9
OBJECTIVES
Explain chemical bonding in terms of the behavior of electrons
Major Understandings:
 Chemical bonds are formed when valence electrons are:
- transferred from one atom to another (ionic)
- shared between atoms (covalent)
- mobile within a metal (metallic)
 Atoms attain a stable valence electron configuration by bonding with other atoms.
Noble gases have stable valence configurations and tend not to bond.
 In a multiple covalent bond, more than one pair of electrons are shared between two atoms. Unsaturated
organic compounds contain at least one double or triple bond.
 Two major categories of compounds are ionic and molecular (covalent) compounds.
 Metals tend to react with nonmetals to form ionic compounds. Nonmetals tend to react with other
nonmetals to form molecular (covalent) compounds. Ionic compounds containing polyatomic ions have
both ionic and covalent bonding.
 When a bond is broken, energy is absorbed. When a bond is formed, energy is released.
 Electronegativity indicates how strongly an atom of an element attracts electrons in a chemical bond.
Electronegativity values are assigned according to arbitrary scales.
 The electronegativity difference between two bonded atoms is used to assess the degree of polarity in the
bond.
 Molecular polarity can be determined by the shape of the molecule and distribution of charge. Symmetrical
(nonpolar) molecules include CO2, CH4, and diatomic elements.
Asymmetrical (polar) molecules include HCl, NH3, and H2O.
 Intermolecular forces created by the unequal distribution of charge result in varying degrees of attraction
between molecules. Hydrogen bonding is an example of a strong intermolecular force.
 Physical properties of substances can be explained in terms of chemical bonds and intermolecular forces.
These properties include conductivity, malleability, solubility, hardness, melting point, and boiling point.
A chemical bond is the force that holds molecules together.
Different types of bonds account for different properties
observed in diverse substances.
Octet Rule = In forming compounds, elements tend to achieve
the electron configuration of a noble gas.
When a chemical bond is formed, the resulting compound has
less potential energy that the substances from which it was
formed. This energy is always released when bonds are formed.
Therefore, making a chemical bond is considered
______________________. (Energy is a product and is
released)
Energy is required to overcome the attractive forces of these
bonds.
Therefore, breaking bonds is ____________________. (Energy
is a reactant and is absorbed)
1. To break a chemical bond, energy must be
a) absorbed
b) destroyed
c) produced
d) released
2. In the following balanced equation representing a
reaction: 2NaCl  2Na + Cl2 the bonds are:
a) formed and energy is absorbed
b) formed and energy is released
c) broken and energy is absorbed
d) broken and energy is released
IONIC BONDING
When a metal transfers an electron to a nonmetal
Atoms of the metallic elements tend to _______ their valence electrons, leaving a
complete octet in the next-lowest energy level.
A loss of an electron produces a _____________ (positively charged ion)
Na.  Na+ + eMg:  Mg2+ + 2eAtoms of the nonmetallic elements tend to ___________ electrons or to share
electrons with another nonmetallic element to achieve a complete octet.
The gain of negatively charged electrons by a neutral atom produces an ________
.Cl: + e-  :Cl: :O: + 2e-  :O: 2Write the equation for the formation of the ion formed when:
1. A potassium atom loses one electron
2. A zinc electron loses two electrons
3. A fluorine atom gains one electron
4. A hydrogen atom gains one electron
5. A hydrogen atom loses one electron
Ionic Bond =
Compounds composed of cations and anions are called ____________________
Although they are composed of ions, ionic compounds are neutral. The oppositely
charged ions will be attracted together in ratios such that their net charge is zero.
Na. + .Cl: 
1 positively charged sodium ion will balance with 1 negatively charged chlorine
ion
Mg: + .Cl: 
1 positively charged magnesium ion is balanced with 2 negatively charged
chlorine ions
Al + Br 
1 positively charged aluminum ion is balanced with 3 negatively charged bromine
ions
Polyatomic Ions = covalently bonded but form ionic bonds with other ions.
e.g. SO32- ion contains covalent bonds between the S and O atoms. But
SO32- will form an ionic bond with Mg  Mg SO3
SWAP AND DROP find the charges on the individual ions and swap and
drop them to figure out the formula of the product.
Predict the ionic compounds formed from the following elements:
Potassium and oxygen
Magnesium and sulfur
Aluminum with oxygen
NAMING IONIC COMPOUNDS
To name a binary ionic compound place the _______ name first, followed by the
_________ name with an _______ ending.
Note: Polyatomic ions keep their names as is. (see Table E)
NaBr
Cs2O
Strontium Fluoride
Barium Iodide
Working with elements with more than one possible oxidation state
If more than one oxidation state is possible for an element, the name of the
compound must include the oxidation state in (roman numerals) immediately
following the element.
CuO
SnF2
Iron (III) Oxide
Tin (IV) Sulfide
COVALENT BONDING
When 2 or more nonmetals share electrons.
Covalent Bond = A bond formed by the sharing of electron pairs between
Note: Although almost every element is looking for a stable octet, Hydrogen &
Helium are stable with 2 electrons (not 8).
H + :Cl: 
H + O
Multiple Bonds
Single Bonds = 1 pair of shared electrons
Double Bonds = 2 pair of shared electrons
Triple Bonds = 3 pair of shared electrons
Polar vs. Nonpolar bonds (Dipoles)
Nonpolar covalent bond = __________ sharing between two similar atoms
Polar covalent bond = _______________ sharing between dissimilar atoms.
Electrons move closer to the more electronegative atom.
Coordinate covalent bond = when one atom contributes _______________
____________________ in the shared pair
H+ + NH3 
H+ + H 2O 
Polar vs. Nonpolar Molecules
While a bond may be polar, the shape of a molecule may contribute to an overall
nonpolar molecule.
Linear
CO2
Tetrahedral
CF4
Bent
H2O
Pyramidal
NH3
Common molecules worth knowing
H2O
CH4
CO2
NH3
O2
N2
NAMING COVALENT COMPOUNDS
Covalent compounds use prefixes (mono, di, tri, tetra) to indicate multiple atoms
of the same element. (NO MONO IS NEEDED ON THE CATION)
Write the name from the given formula
SO2
SO3
Write the formula from the given name
Carbon Tetrachloride
Carbon Dioxide
NAMING A BINARY COMPOUND
1. [name of Cation] [name of Anion] change ending to –ide
Note: Polyatomic ions keep their names as is. (see Table E)
2. Is the compound ionic? If yes go to #3
Is the compound covalent? If yes go to #4
3. Does the cation have more than one possible oxidation state?
NO = name is complete 
YES = the name of the compound must include the oxidation state in
(roman numerals) immediately following the element. name is complete 
4. Use prefixes (mono, di, tri, tetra) to indicate multiple atoms of the same
element.
Note: No prefix is needed on the cation if there is only 1 of them.
name is complete 
[name of Cation] [name of Anion] change ending to –ide
Note: Polyatomic ions keep their names as is. (see Table E)
IONIC
COVALENT
Does the cation have
more than one possible
oxidation state?
NO
name is complete 
Use prefixes (mono, di, tri, tetra)
to indicate multiple atoms of the
same element.
Note: No prefix is needed on the
cation if there is only 1 of them.
YES
name of the compound must
include the oxidation state in
(roman numerals) immediately
following the element.
METALLIC BONDING
Metal atoms are present as ions, with electrons free to move around (mobile
electrons). Attraction of these free floating electrons to metal cations is a
_____________________________
This structure gives explains many of metals properties including being
conductive, malleable and ductile.
Alloys = mixtures of two or more elements, one of which is a ___________
Alloys have properties which differ from their constituent elements.
e.g. sterling silver (92.5% Ag, 7.5% Cu) is harder and more durable than pure Ag,
but still soft enough to be made into jewelry and tableware.
Bronze is an alloy of 7:1 Cu:Sn
INTERMOLECULAR FORCES OF ATTRACTION
Molecules can attract each other by a variety of forces. While intermolecular
forces are weaker than either ionic or covalent bonds, they are important. They
play a role in determining whether a compound will be solid, liquid or gas.
Van der Waals forces
Dipole – Dipole when oppositely charged regions of ____________
molecules are attracted to each other
Dispersion very weak force, caused by _________________________
(momentary poles)
Stronger when more _________________ are present
(Halogen examples: F, Cl with relatively few electrons are gases, Br with
more electrons is a liquid and I is a solid)
Hydrogen bonding attractive force in which a _____________ that is covalently
bonded to a highly electronegative atom, is also weakly bonded to an unshared
electron pair of another electronegative atom.
Strongest of the intermolecular forces
e.g.
In general, the more polar the bond  stronger forces  higher melting points
(and sometimes boiling points too)
TYPES OF SUBSTANCES
IONIC COMPOUNDS a 3 dimensional framework of ____________ (table salt)
 Hardness  Conductivity  Melting point  Example -
COVALENT MOLECULAR COMPOUNDS individual covalent molecules
________________________ by intermolecular bonds (sugar)
 Hardness  Conductivity  Melting point  Example COVALENT NETWORK COMPOUNDS a 3 dimensional framework of ___________
 Hardness  Conductivity  Melting point  Example -
METALLIC metal ions surrounded by __________________
 Hardness  Conductivity  Melting point  Example -
Type
Particles in
substance
Primary
IMF
Hardness
Conductivity
Melting
Point
Examples
Ionic
Covalent
molecular
Covalent
network
Metallic
1. The electrical conductivity of KI (aq) is greater than the electrical
conductivity of H2O (l) because the KI (aq) contains
a) Molecules of H2O
c) ions from H2O
b) Molecules of KI
d) ions from KI
2. Which factor distinguishes a metallic bond from an ionic or covalent bond?
a) The mobility of electrons
c) the equal sharing of electrons
b) The mobility of protons
c) the unequal sharing of electrons
3. Which substance has a high melting point and conducts electricity in the
liquid phase?
a) Ne
b) Hg
c) NaCl
d) CO
4. Which substance is a conductor of electricity?
a) NaCl (s)
b) NaCl (l)
c) C6H12O6 (s)
d) C6H12O6 (l)
NAME: _______________________________________
BONDING
BIG IDEAS
FORMULAS
REFERENCE TABLES
Alloy
Bent
Coordinate covalent bond
Covalent bond
Covalent molecular compound
Covalent network compound
Dipole
Dipole-dipole
Dispersion
Double bond
Endothermic
Exothermic
Hydrogen bond
Ionic bond
Ionic compound
Intermolecular
Intermolecular force of attraction
Intramolecular
Linear
Metallic bond
Nonpolar covalent bond
Nonpolar molecule
Polar covalent bond
Polar molecule
Polyatomic ion
Pyramidal
Single bond
Symmetrical
Tetrahedral
Triple bond