Describe the relationship between group number and the charge of the ions formed from elements in that group

Describe relative atomic mass, ( A_r ), as the average mass of the isotopes of an element compared to 1/12th of the mass of an atom of ( ^{12}C )

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