QUESTION 2 (Start on a new page.) The letters A to F in the table represent SIX substances:

The electronegativity of Li is approximately 1.0.
The electronegativity of F is approximately 4.0.

Since the electronegativity difference (3.0) is greater than 1.7, the bond between Li and F is predominantly ionic.

2.5
The Lewis structure for substance B ($\text{N}_2$) is:

Nitrogen gas ($\text{N}_2$) is unreactive at room temperature and normal pressures because it contains a very strong triple covalent bond between the two nitrogen atoms. A large amount of energy is required to break this bond, making it difficult for $\text{N}_2$ to react.

2.6.1
The ion formed when substance C ($\text{NH}_3$) reacts with the $\text{H}^+$ ion is the ammonium ion ($\text{NH}_4^+$).

2.6.2
Two requirements for the formation of dative covalent bonds are:

• One atom must have a lone pair of electrons to donate.
• Another atom or ion must have an empty orbital to accept the lone pair of electrons.