Covalent Bonding

Covalent Bonding

• The strong, electrostatic forces of attraction between shared paired of electrons and the bonded atom’s nuclei

Covalent Bonding between atoms

• Non-metallic

• Compounds of non-metallic elements

• Polyatomic ions

Covalent Bond - orbital overlap

• It is the overlap of atomic orbitals, each containing 1 electron, to provide a shared pair of electrons

Covalent Bond - attraction

• The attraction is localised (it acts solely between the shared pairs of electrons and the nuclei of the 2 bonded atoms - forms a molecule)

Displayed Formula

• A structure showing the relative positioning of atoms and bonds between them as lines

Lone Pair

• Paired electrons that are not shared

H₂O Covalent Bond

NH₃ Covalent Bond

Number of Covalent Bonds (common elements)

• C - 4 bonds

• N - 3 bonds

• O - 2 bonds

• H - 1 bond

Elements in Period 2

• Maximum 8 electrons in the outer shell

Elements in Period 3

• Can have more than 8 electrons in the outer shell (octet)

Multiple Covalent Bonds

• 2 atoms sharing more than 1 pair of electrons

Dative Covalent Bonds

• When the shared pair of electrons have been supplied by one of the bonding atoms only (e.g, NH₄)

Formation of Dative Covalent Bonds

• The shared electron pair was originally a loan pair of electrons 

• E.g, formation of an ammonium ion - ammonia donates the loan pair of electrons to an H+ ion (shown by an arrowhead)

Average Bond Enthalpy

• A measurement of covalent bond strength