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Covalent Bonds
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent BondCovalent Bond
Covalent BondCovalent Bond
Covalent Bond
• Bond that is usually formed between by• Non-metal such as hydrogen , carbon and oxygen
do not lose electron from their outer shell .• They do not form positive ions by losing electrons .
However their outer shells are incomplete. • Electron need to be added to the outer shells to
attain the stability of the noble gas atoms.• When the atoms of two non-metals react , all the
atom need to gain electrons to complete the octet shell of electrons. They can do this by sharing electrons between them .
sharing of electronnon-metal atoms
Lewis Structure
• Shows how the valence electrons of the atoms are arranged in the molecules .
• Example
a ) A helium atom has two valence electron *click to see
He ..
b ) A neon atom has eight valence electrons
Ne ::. .
. .
• Rules for Writing Lewis Structuresi ) Add up the valence electrons of all the atom in the molecule. Example : CO2
: C : O O = 16 valence electrons
ii ) Use a pair of electrons to form a bond between each pair of atomsiii ) Arrange it like this
x x o o
x x
o o
x x o o
O : C : O
xxxx
xx
oo oo
oo
Another example : Hydrogen
H HXO
HH O x
OxygenO2
ChlorineCl2
IodineI2
NitrogenN2
Phosphorus
P4
SulphurS8
Other molecules the are held together by covalent bond
Single Bond
Chlorine Molecule
ClCl
Cl Cl
Cl Cl
Cl Cl
Cl Cloctet
Cl Cloctet
Cl ClThe octet is achieved byeach atom sharing theelectron pair in the middle
Cl ClThe octet is achieved byeach atom sharing theelectron pair in the middle
Cl ClThis is the bonding pair
Cl ClIt is a single bonding pair
Cl ClIt is called a SINGLE BOND
Double bond can also be shown as single dash
Cl - Cl
Water• H2O
Methane• CH4
Tetrachloromethane• CCL4
Ammonia• NH3
Another example of Single Bond
Double Bond
sometimes simple is better -_-
Oxygen
How will two oxygen atoms bond?
OO
OOEach atom has two unpaired electrons
OO
OO
OO
OO
OO
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
OO
OO
OO
OO
OOBoth electron pairs are shared.
6 valence electronsplus 2 shared electrons
= full octet
OO
6 valence electronsplus 2 shared electrons
= full octet
OO
two bonding pairs,
OOmaking a double bond
Double bond can also be shown as double dashes
O = O
Carbon Dioxide•CO2