Covalent Bonding
Many compounds do not form ionic bonds.
These compounds contain two or more nonmetallic atoms.
 For example, CO2 is made of two different
non-metals, carbon and oxygen. These
compounds are formed through the sharing
of valence electrons.

A covalent bond is formed when two
or more non-metallic atoms share
valence electrons.
 Non-metallic atom + Non-metallic
atom = covalent bonding

Compounds vs. Molecules
Two non-metallic elements combine to
form covalent compounds (or bonds).
Compounds contain at least two
different types of atoms.
 A molecule is the smallest unit of a
covalent compound.
 A molecule of a compound has
different characteristic properties
than the atoms which form it.

Example

Two hydrogen atoms form a covalent
bond by sharing electrons to produce a
hydrogen molecule. A hydrogen
molecule still possesses the properties
of hydrogen. No new substance is
formed since only one type of atom, H,
is present.

By sharing their electrons, both atoms
are satisfied they have filled outer orbits
(the outer orbits are the same as for
helium) and are stable.

The two hydrogen atoms form a
diatomic molecule (i.e., two atoms of
hydrogen share electrons to make a
single molecule of hydrogen gas).
The elements forming diatomic gases are
unstable as single atoms and combine
almost instantaneously to form stable
molecules.
 Note that diatomic molecules are still
classified as elements even though they
are molecules. While it may seem strange
that a molecule is called an element rather
than a compound, remember that diatomic
molecules are made of only one kind of
atom.

Name of
Element
Symbol for
one atom of
the element
Formula or
one molecule
of the
element
Hydrogen
H
H2(gas)
Nitrogen
N
N2(gas)
Oxygen
O
O2(gas)
Fluorine
F
F2(gas)
Chlorine
Cl
Cl2(gas)
Bromine
Br
Br2(liquid)
Iodine
I
I2(solid)
HINT!!!!
If the diatomic elements are placed
in a different order the symbols spell
out a word that can help you remember
these diatomic elements.
 Remember “Count HOFBrINCl”,
pronounced as “Count Hoffbrinkle”. If
you remember “Count HOFBrINCl” you
will never forget which elements are
diatomic

Organic Compounds
Covalent bonds can also be
classified as organic compounds.
This is when 2 non-metallic elements
combine together.
 Example: e.g. CO , C H O

Diatomic or Organic Compound?
Example – If the element
was on it’s own...
Fluorine
Carbon
Sulphur
Hydrogen
Helium
Chlorine
Oxygen
Forms a Diatomic or
Organic Compound?
Octet Rule



The only way that two non-metallic atoms can
satisfy their need to gain electrons when they
bond is through sharing valence electrons.
The sharing of electrons between two nonmetallic atoms allows each atom to have a
complete octet of electrons at least part of the
time.
The shared electrons are attracted at the
same time to each nucleus in each atom. This
is the “glue” that holds the atoms together.
A covalent bond is formed when two atoms
share one or more pairs of electrons in order
to obtain a complete octet of electrons.
Happy Atoms!