Question

what is valancy?... ​

Answer 1

The capability of an atom to gain or lose its valence electrons in order to complete it's valence shell ( last shell) is known as valency.

For Example,

SODIUM

- 11

ELECTRONIC CONFIGURATION- K-2,L-8,M-1

Atom of every element wants to have eight electrons in it's valence shell. As you can see above sodium has one electron in it's valence shell. In order to get a completely filled outermost shell it has to lose this one electron. So, it will have a valency of 1.

SULPHUR

ATOMIC NUMBER- 16

ELECTRONIC CONFIGURATION- K-2, L-8, M-6

As, sulphur has six electrons in it's valence shell it has to gain 2 more electrons to have a full valence shell and it will have a valency of 2.

Answer 2

the combining power of an element, especially as measured by the number of hydrogen atoms it can displace or combine with.