Question

The electronic configuration of an element X is 2, 8, 7.
1. What is the atomic number of the element X?
2. Is X metal or non-metal?
3. What is the valency of X?

Answer 1

Answer:

chlorine and it is non metal because it is a gas and it's valency is -1

Answer 2

Answer:

atomic no.17....non metal....(minus 1) is the valancy

Explanation:

atomic no. of an element is the sum of it's electronic configuration......

i.e 2+8+7=17.....

since to complete it's octate it requires one more electron....which shows electron defficiency ....which is property of non-metal.......

valency is the no. of electrons required to obtain the Noble gas configuration ...

which is here (minus 1).....

hope u understood...