1. Compounds
Part two: Molecular compounds

2. Molecular Compounds
• A molecule is a combination of
two or more atoms held
together by covalent bonds
• A covalent bond occurs
between the atoms of non-
metals in which the two atoms
share a pair of electrons

3. Molecular Elements
• A molecular element is when
two or more atoms of the same
element are joined by covalent
bonds
• A diatomic molecule is a
molecule that is made from two
atoms e.g.) the element chlorine
is a diatomic molecule (Cl2)

4. Molecular Compounds
• When atoms of two or more
different non-metals combine,
a pure substance known as a
molecular compound is
formed

5. Molecular Compounds
• As with molecular elements,
the atoms in molecular
compounds are joined
together by covalent bonds
• In each bond, the atoms share
a single pair of electrons.

6. Molecular Compounds
• For example, water is a
molecular compound with two
covalent bonds
• Each hydrogen atom shares
one pair of electrons with an
oxygen atom

7. Properties of Molecular
Compounds
• soft
• low melting point
• solutions do not conduct
electricity

8. Naming Molecular
Compounds
For compounds that do not
contain hydrogen:
1. Name the first element
2. Name the second element and
change the ending to “-ide”
3. add prefixes to indicate the
number of each atom

9. Naming Molecular
Compounds
• The prefix “mono” is not used
when there is only one atom
of the first element
• When “mono” is being added
to oxygen, the last “o” is
dropped (e.g. “monoxide” not
“monooxide”)

10. Naming Molecular
Compounds
Example 1: N2O
• Name the first element:
nitrogen
• Name the second element
using “-ide”: oxide
• Add prefixes:
dinitrogen monixide

11. Naming Molecular
Compounds
Example 2: PBr3
• Name the first element:
phosphorous
• Name the second element
using “-ide”: bromide
• Add prefixes:
phosphorous tribromide

12. Naming Molecular
Compounds
• Hydrogen is unique in many
ways, and this is reflected in the
naming systems
• Many compounds containing
hydrogen have been given
simpler names
• For example, dihydrogen
monoxide (H2O) is simply
called “water”

13. Naming Molecular
Compounds