Topic 3: Bonding
Ionic bonding
Ionic bonding involves electrostatic attraction between oppositely charged ions in a lattice.
SO₄²- (sulfate)
OH− (hydroxide)
NO3- (nitrate)
CO3(2−) (carbonate)
NH4+ (ammonium)
Group 1: +1
Group 2: +2
Group 3: +3
Group 4: +4
Group 5: -3
Group 6: -2
Group 7: -1
Group 8 - 0
When constructing formulas for ionic compounds, make sure the charges of each element
balance each other out. Eg. Na+ and Cl- make NaCl because the charges are balanced.
Nature of covalent and dative bonding
A single covalent bond contains a shared pair of electrons.
Multiple bonds contain multiple pairs of electrons.
A co-ordinate (dative covalent) bond contains a shared pair of electrons with both electrons
from one atom.
Covalent bond: ---
Dative bond: →
Metallic bonding
Metallic bonding involves attraction between delocalised electrons and positive ions
arranged in a lattice.
, Shapes of simple molecules and ions
Bonding pairs - electron pairs that are shared
Lone pairs - electron pairs that are not shared
These pairs of electrons are repelled by each other.
Pairs of electrons in the outer shell of atoms arrange themselves as far apart as possible to
minimise repulsion
Lone pair–lone pair repulsion > lone pair–bond pair repulsion > bond pair–bond pair
repulsion.
Linear (XY2)
Trigonal planar (XY3)
Tetrahedral (XY4)
Trigonal pyramidal (NH3)
Bent (X2Y)
Trigonal bipyramidal (XY5)
Ionic bonding
Ionic bonding involves electrostatic attraction between oppositely charged ions in a lattice.
SO₄²- (sulfate)
OH− (hydroxide)
NO3- (nitrate)
CO3(2−) (carbonate)
NH4+ (ammonium)
Group 1: +1
Group 2: +2
Group 3: +3
Group 4: +4
Group 5: -3
Group 6: -2
Group 7: -1
Group 8 - 0
When constructing formulas for ionic compounds, make sure the charges of each element
balance each other out. Eg. Na+ and Cl- make NaCl because the charges are balanced.
Nature of covalent and dative bonding
A single covalent bond contains a shared pair of electrons.
Multiple bonds contain multiple pairs of electrons.
A co-ordinate (dative covalent) bond contains a shared pair of electrons with both electrons
from one atom.
Covalent bond: ---
Dative bond: →
Metallic bonding
Metallic bonding involves attraction between delocalised electrons and positive ions
arranged in a lattice.
, Shapes of simple molecules and ions
Bonding pairs - electron pairs that are shared
Lone pairs - electron pairs that are not shared
These pairs of electrons are repelled by each other.
Pairs of electrons in the outer shell of atoms arrange themselves as far apart as possible to
minimise repulsion
Lone pair–lone pair repulsion > lone pair–bond pair repulsion > bond pair–bond pair
repulsion.
Linear (XY2)
Trigonal planar (XY3)
Tetrahedral (XY4)
Trigonal pyramidal (NH3)
Bent (X2Y)
Trigonal bipyramidal (XY5)
