Question

Define valency by taking example of silicon and oxygen.

Answer 1

Answer:-

The number of electrons gained, lost or shared so as to complete the octet of electrons in valence shell is called valency.

Valency of silicon: It has electronic configuration → 2,8.4

Thus, 4 electrons are shared with other atoms to complete the octet and so its valency = 4

Valency of oxygen : It has electronic configuration →2,6

Thus, It will gain 2 electrons to complete its octet. So its valency = 2

hope it helps you

Answer 2

$\textbf{Valency}$

Valency of an element is defined as its capacity to combine with other elements.

Si has valency of 4, as its outer most cell have 4 electrons.

O has 2 valency, as its outermost cell have 6 electrons.