Determine the valencies of the elements by the formula of the substance: a) Na2O; b) BaCl2; c) NO;

Determine the valencies of the elements by the formula of the substance: a) Na2O; b) BaCl2; c) NO; d) CH4 Name the substances.

Na2O – sodium oxide. Valence of sodium I, oxygen – II.

We find the valence of sodium according to the periodic table, sodium is in group I, the valency coincides with the group number. The oxygen valence is always II (with some exceptions).

BaCl2 is barium chloride. The valence of barium is II (determined by the group number), chlorine is I (denoted by x, we will make the equation: 2 + 2x = 0, x = 1).

NO-azoa (II) oxide. The valence of nitrogen is II (we find it by oxygen, making the equation: x + 2 = 0, x = 2); oxygen valence II.

CH4 is carbon hydride. The valence of carbon is IV, the valence of hydrogen is I.