Valency

Write the chart of the valency of the first thirty elements.

The combining capacity of an element is known as _____ (mass/valency).

The chemical formula of a molecular compound is determined by _____ of each element.

Classify the following ions into monovalent, divalent and trivalent.
${\mathrm{Ni}}^{2+}, {\mathrm{Fe}}^{3+}, {\mathrm{Cu}}^{2+}, {\mathrm{Ba}}^{2+}, {\mathrm{Cs}}^{+}, {\mathrm{Zn}}^{2+}, {\mathrm{Cd}}^{2+}, {\mathrm{Hg}}^{2+}, {\mathrm{Pb}}^{2+}, {\mathrm{Mn}}^{2+}, {\mathrm{Fe}}^{2+}, {\mathrm{Co}}^{2+}, {\mathrm{Sr}}^{2+}, {\mathrm{Cr}}^{3+}, {\mathrm{Li}}^{+}, {\mathrm{Ca}}^{2+}, {\mathrm{Al}}^{3+}$

The element exhibiting variable valency is: