Question #f444a

May 12, 2017

No, they cancel out.

Explanation:

Valency is the combining power of an element.

Let's use $C {a}^{2 +}$ and ${O}^{2 -}$

Valency of $C {a}^{2 +}$= 2
Valency of ${O}^{2 -}$= 2

When they combine, they cancel out into $C a O$.

(Don't put this on the exam, but you can think of the formula looking like $C {a}_{2} {O}_{2}$ before they cancel out)

Let's use one more example: ${K}^{+}$ and ${O}^{2 -}$

Valency of ${K}^{+}$= 1
Valency of ${O}^{2 -}$= 2

When they combine, we basically switch the valencies so that the 2 goes by the $K$ and the 1 goes by the $O$

So ${K}_{2} {O}_{1}$ but the 1 is understood so we don't write that in the final formula which is ${K}_{2} O$