5.3 - Covalent Bonding

Question 1

Define covalent bonding.

Answer 1

Electrostatic attraction between shared electron pairs and the nuclei of bonded atoms

Occurs between:

• Non metallic elements
• Compounds on non-metallic elements
• Polyatomic ions (e.g. NH₄⁺)

Question 2

How is the covalent bond formed?

Answer 2

• They are overlaps of orbitals, each contributing 1 electron to the bond (giving a shared pair of electrons)
• Shared pair is attracted to the nuclei of both the bonding atoms
• Bonded atoms have outer shells with same electron structure as the nearest noble gas

Question 3

In terms of how localised the bond is, how does a covalent bond compare to an ionic bond?

Answer 3

• Ionic bonds have attraction all around the ion
• Covalent bond’s attraction is only between the electron pairs and the nuclei of the bonded atoms
  
  • attraction is localised
    
    • results in molecule - smallest part of a covalent compound that can exist on its own whilst retaining chemical properties of the compound (has 2 or more atoms)

Question 4

What is a double covalent bond?

Answer 4

Electrostatic attraction between 2 shared pairs of electrons and the nuclei, electron structure of the nearest noble gas

E.g. O=O, O=C=O

Question 5

What is a triple covalent bond?

Answer 5

• Electrostatic attraction between 3 shared pairs of electrons
• Has electron structure of nearest noble gas

E.g. H-C≡N

Question 6

What is a dative covalent bond?

Answer 6

AKA coordinate bond

• Covalent bond where shared pair of electrons is only from one of the bonded atoms
• Dative covalent bond, electron pair was originally a lone pair

e.g. NH₄⁺ formation, NH₃ + H⁺

Ammonia donates electron pair to H⁺