Formation of covalent bonds Formulas of molecular compounds LEWIS STRUCTURE Molecules of Elements Molecules of Compounds Non-Polar Covalent Bond Polar Covalent Bond Uses of Covalent bonds Real life application

1. General Chemistry
COVALENT BONDS

2. Covalent Bonds
1
Formation of
covalent
bonds
2
Formulas of
molecular
compounds
3
Lewis
structure of
molecules
4
Molecules of
elements
5
Molecules of
compounds
6
Structure and
properties of
molecular
compounds

3. NONMETAL + NONMETAL = COVALENT BOND
Covalent bonding occurs when 2 or more nonmetal atoms share
electrons to achieve a full outer shell of electrons.
Covalent Bonds
1
Formation
of covalent
bonds
tends to gain
electrons by sharing

4. Prefixes which indicate the number of atoms of
each element are used in the naming of inorganic
molecular compounds. You should memorize the
following:
Mono 1 Hexa 6
Di 2 Hepta 7
Tri 3 Octa 8
Tetra 4 Nona 9
Penta 5 Deca 10
2
Formulas of
molecular
compounds

5. Covalent Bonds
3
Lewis
structure of
molecules
Lewis
Structure
Electron-dot
structure
Gilbert Newton Lewis
–(1969)
He propose that a sharing of two
electrons by two hydrogen atoms permits
each one to have a stable closed-shell
electron configuration analogue to
helium.
LEWIS STRUCTURE

6. Covalent Bonds
LEWIS STRUCTURE 3
Lewis
structure of
molecules
Draw Lewis structures step by step:
Step 1: Determine the total number of valence electrons.
Step 2: Write the skeleton structure of the molecule.
Step 3: Use two valence electrons to form each bond in the skeleton structure.
Step 4: Try to satisfy the octets of the atoms by distributing the remaining
valence electrons as nonbonding electrons.

7. Covalent Bonds
lose, gain or share electrons to achieve a full valence shell.
Octet Rule
Example.
Nitrogen and Neon
• Single Bond
• Double Bond
• Triple Bond

8. Covalent Bonds
Single Bond
A single bond is when two electrons--one pair of electrons--are
shared between two atoms.
❖H2O
❖PCl3

9. Covalent Bonds
Double Bond
A Double bond is when two atoms share two pairs of electrons
with each other.
❖O2
❖PO4
–3

10. Covalent Bonds
Triple
Bond
A Triple bond is when three pairs of electrons are shared
between two atoms in a molecule.
❖F2
❖C2H2

11. CH4 SO2
H2S HCN CH3CH2OH
Draw Lewis Dot structures for the ff. compounds:

12. Covalent Bonds
4
Molecules of
elements
Molecules of Elements

13. Covalent Bonds
Organic and Inorganic
C12H22O11
5
Molecules of
compounds
Molecules of Compounds

14. Covalent Bonds
Polar Covalent Bond
Non-Polar Covalent
Bond
4 2 6 2 4
– the shared electrons between
atoms are equally shared.
– the shared electrons between
atoms are not equally shared.
H2
Cl2
CO2
H2O
HCN
δ+
δ–

15. Covalent Bonds
Properties of simple molecular substances
• Low melting and boiling points - This is because the weak intermolecular forces break
down easily.
• Non-conductive - Substances with a simple molecular structure do
not conduct electricity. This is because they do not have any free electrons or an
overall electric charge.
6
Structure and
properties of
molecular
compounds
Covalently bonded substances fall into two main types:

16. Covalent Bonds
Covalently bonded substances fall into two main types:
2. Giant Covalent structures
Giant covalent structures contain a lot of non-metal atoms, each joined to adjacent atoms
by covalent bonds. The atoms are usually arranged into giant regular lattices - extremely
strong structures because of the many bonds involved.
Properties of giant covalent structures
• Very high melting points - This because a lot of strong covalent bonds must be broken.
Graphite, for example, has a melting point of more than 3,600ºC.
• Variable conductivity - Diamond does not conduct electricity. Graphite contains
free electrons, so it does conduct electricity. Silicon is semi-conductive - that is,
midway between non-conductive and conductive.

17. Covalent Bonds
Graphite
Graphite is a form of carbon in which the carbon atoms form layers. These
layers can slide over each other, so graphite is much softer than diamond. It
is used in pencils, and as a lubricant. Each carbon atom in a layer is joined to
only three other carbon atoms. Graphite conducts electricity.
Diamond
Diamond is a form of carbon in which each carbon atom is joined to four
other carbon atoms, forming a giant covalent structure. As a result,
diamond is very hard and has a high melting point. It does not conduct
electricity.
Silica
Silica, which is found in sand, has a similar structure to diamond. It is also
hard and has a high melting point, but contains silicon and oxygen atoms,
instead of carbon atoms. The fact that it is a semi-conductor makes it
immensely useful in the electronics industry: most transistors are made of
silica.
Buckminsterfullerene
Buckminsterfullerene is yet another allotrope of carbon. It is actually not a
giant covalent structure, but a giant molecule in which the carbon atoms
form pentagons and hexagons - in a similar way to a leather football. It is
used in lubricants.

18. Covalent Bonds