Represent the following atoms using Lewis notation:

Beryllium

Represent the following atoms using Lewis notation:

Calcium

Represent the following atoms using Lewis notation:

Lithium

Two chemical reactions are described below.

(i) Nitrogen and hydrogen react to form ammonia $\left({\mathrm{NH}}_3\right)$.

(ii) Carbon and hydrogen bond to form a molecule of methane $\left({\mathrm{CH}}_4\right)$.

For each reaction give the valency of each of the atoms involved in the reaction.