Bonding
There are two types of bonding
 Ionic – transfer of electron
 Covalent – sharing of electrons
We determine the bond based on electronegativity. If the electronegativity difference is large
then the electron is transferred. If the electronegativity difference is low then the electron is
shared. Below is a break down for the different types of bonding.
Type of bond
Electronegativity difference
Example
Non-polar covalent
0.0 – 0.4
H–H
Polar Covalent
0.5 – 2.0
H – Cl
Ionic
2.0 +
Na - F
Ionic Bonding
Ions

Cation – is a positively charged ion. This happens when a neutral atom loses an
electron(s) causing there to be more protons than electrons. Now the atom is positively
charged cation.
 Anion – is a negatively charged ion. This happens when a neutral atom gains an
electron(s) causing there to be more electrons than protons. Now the atom is a negatively
charged anion.
Naming
Name of the cation, if it is a transition metal must have roman numeral that tells the charge.
Followed by the name of the anion, change the ending to –ide. If it is a polyatomic ion then leave
the ending as listed as –ite or –ate. Ex. NaCl – Sodium Chloride; KNO3 – potassium nitrate;
Fe2O3 – Iron (III) oxide
Covalent Bonding
Diatomic Molecules
The Noble gases are atoms that will never bond with any other atom, because they
already have 8 valence electrons, hence the basis for the octet rule. These would be called
monatomic atoms, there are also diatomic molecules. The term diatomic means molecules will
exist as 2 atoms and never alone. Such as the Oxygen we breathe in which is called O2. There are
7 diatomic molecules HONI and up
Hydrogen H2, Oxygen O2, Nitrogen, N2 Iodine I2, Bromine Br2, Chlorine Cl2 and
Fluorine F2.
Naming Molecular Compounds
To name molecular compounds we must use prefixes, which tell the numver of each atom
that is present in the molecule.
Prefix
Mono- DiTriTetra- Penta- Hexa- Hepta- Octa- nona Decanumber 1
2
3
4
5
6
7
8
9
10
The steps to naming molecular compounds is as follows:
 Write the name of the first listed element with the prefix for how many atoms are present.
Omit the mono- for the first name.
 Followed by the name of the second compound with the prefix for how many atoms are
present. Always change the ending to –ide.
Lewis Dot Structure
Each dot represents a valence electron, so the group number gives the number of dots
each atom gets. Then, instead of transferring electrons from the metal to the nonmetal, as in ionic
bonding, we will show where each set of electrons will pair up in a bond, which is represented as
a “dash” .
Exceptions
There are a few exceptions to the octet rule that you should be aware of and they are
listed below with the number of electrons they can attain
H–2
P – 10
B–6
S - 12
Intermolecular Forces
The three types of intermolecular forces are London dispersion, dipole-dipole, and hydrogen
bonding. All intermolecular forces are weaker then ionic or covalent bonds, but London
dispersion forces are the weakest of all the molecular forces and they occur between all
molecules. Dipole-Dipole attractions can only occur when the molecule is polar. While
hydrogen bonding can occur when you have a hydrogen atom bonded to a F, O, or N. This is
because these three atoms will always have a lone pair of electrons. The intermolecular forces
help to explain why some molecules are solid, liquid, or gas no matter what their size.
Characteristic
Ionic Compound
Covalent Compound
Bond Formation
Transfer of electrons
Sharing of electrons
Types of elements
Metal – Nonmetal
Nonmetal – nonmetal
Physical state
solids
Solid, liquid, gas
Melting point
High
Low to high
Electronegativity strength
Weak- strong
Strong - Strong