Describe the formation of covalent bonds in simple molecules, including ( CH_3OH ), ( C_2H_4 ), ( O_2 ), ( CO_2 ) and ( N_2 ). Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules

Describe the reactions, if any, of: (a) potassium, sodium and calcium with cold water (b) magnesium with steam (c) magnesium, zinc, iron, copper, silver and gold with dilute hydrochloric acid and explain these reactions in terms of the position of the metals in the reactivity series