Question

The atom of an element X has 7 electrons in its M shell.

(a) Write the electronic configuration of element X.

(b) What is the atomic number of element X?

(c) Is it a metal or a non-metal?

(d) What type of ion will be formed by an atom of element X? Write the symbol of the ion formed.

(e) What could element X be?

Answer 1

(a) Electronic configuration of the element X is
Element X: $\underset{2}{\mathrm{K}}\underset{8}{\mathrm{L}}\underset{7}{\mathrm{M}}$
(b) Atomic number of the element X will be 17.

(c) Element X is a non-metal because there are 7 electrons in its outermost orbit. In order to complete its octet (to get 8 electrons), it will gain one electron. An element which gains electrons in order to complete its octet is a non-metal.

(d) The element will form an anion by gaining an extra electron in order to complete its octet.
Symbol of an ion of X will be X^–.

(e) X is Chlorine.