Bonding
, Covalent Bonding
Covalent bonding occurs between:
non-metals and non-metals
X
Non-metals and metals
*
Covalent bonds involve sharing a pair of electrons
! The shared electrons are attracted to both nuclei
Particle produced is called a molecule or giant covalent
↑
When covalent bonds are formed, a new molecular orbital is formed because the two orbitals
overlap to produce an area of high electron density
↑
You can represent one pair of shared electrons in a covalent bond by a line.
How does sharing electrons hold atoms together?
Atoms with covalent bonds are held together by the electrostatic attraction between the
nuclei and the shared electrons.
*
Repulsion does occur however the forces are balanced when the nuclei are a particular
distance apart.
Co-ordinate
Double Covalent Bonds NH,: -
covalent
I
4 electrons are shared bond
x5 *
Represented by a double line e.g. O=O
↑
H · H
Triple Covalent Bonds
↳
6 electrons are shared ⑧
↑
Represented by a triple line e.g. N=N H
Properties of substances with molecular structure
Substances composed of molecules are gases, liquids or solids with low melting temperatures
D
This is because the strong covalent bonds are only between the atoms within the molecule.
There are only weak attractions between the molecules so the molecules don’t need much
energy to move apart from each other.
Poor conductors of electricity because molecules are generally neutral.
&
Co-ordinate Bonding (dative covalent Bonding)
A single covalent bond consists of a pair of electrons shared between two atoms, in a co-
ordinate bond one atom provides both electrons.
In a co-ordinate bond:
The atoms that accepts the electron pair is an atom that does not have a filled outer main
level of electrons
The atom that is donating the electrons has a pair that is not being used in a bond: lone pair.
H t
·
Represented by arrows
e.g. i Co-ordinate bonds have exactly the same strength
HN, and length as ordinary covalent bonds
Dot and cross diagram for boron trifluoride
= 2t
Is to t
8 F E
E
=
xX
, Covalent Bonding
Covalent bonding occurs between:
non-metals and non-metals
X
Non-metals and metals
*
Covalent bonds involve sharing a pair of electrons
! The shared electrons are attracted to both nuclei
Particle produced is called a molecule or giant covalent
↑
When covalent bonds are formed, a new molecular orbital is formed because the two orbitals
overlap to produce an area of high electron density
↑
You can represent one pair of shared electrons in a covalent bond by a line.
How does sharing electrons hold atoms together?
Atoms with covalent bonds are held together by the electrostatic attraction between the
nuclei and the shared electrons.
*
Repulsion does occur however the forces are balanced when the nuclei are a particular
distance apart.
Co-ordinate
Double Covalent Bonds NH,: -
covalent
I
4 electrons are shared bond
x5 *
Represented by a double line e.g. O=O
↑
H · H
Triple Covalent Bonds
↳
6 electrons are shared ⑧
↑
Represented by a triple line e.g. N=N H
Properties of substances with molecular structure
Substances composed of molecules are gases, liquids or solids with low melting temperatures
D
This is because the strong covalent bonds are only between the atoms within the molecule.
There are only weak attractions between the molecules so the molecules don’t need much
energy to move apart from each other.
Poor conductors of electricity because molecules are generally neutral.
&
Co-ordinate Bonding (dative covalent Bonding)
A single covalent bond consists of a pair of electrons shared between two atoms, in a co-
ordinate bond one atom provides both electrons.
In a co-ordinate bond:
The atoms that accepts the electron pair is an atom that does not have a filled outer main
level of electrons
The atom that is donating the electrons has a pair that is not being used in a bond: lone pair.
H t
·
Represented by arrows
e.g. i Co-ordinate bonds have exactly the same strength
HN, and length as ordinary covalent bonds
Dot and cross diagram for boron trifluoride
= 2t
Is to t
8 F E
E
=
xX
