Question

How many electrons are in the outermost energy level of the chloride ion in table salt?

Answer 1

Hint: The nucleus of an atom is surrounded by the electron clouds having a number of electrons depending upon the specific atom or ions.
As per the octet rule, the atoms having outermost configuration of eight electrons, are the most stable form of them. So, the atoms tend to lose or gain electrons as per the need.

Complete step by step solution:
In order to answer this question, we must first consider the electronic configuration of the chlorine atom. It is \[\left[ Ne \right]3s{}^{2}3{{p}^{5}}\] and as we can see the outermost shell has only five electrons at the ‘p’ orbital, and it needs one more to attain a stable octet configuration. So, in case of sodium chloride which is the table salt, the chlorine is negatively charged, as it gained one electron from the sodium atom and became anion and the sodium became cation as a result. Chlorine atoms have seventeen electrons and chlorine ions have eighteen electrons. The sodium chloride is represented by the formula $NaCl$ and it is an ionic solute, as both the atoms are attached to each other in their ionic forms. They experience the attraction towards each other because of the opposite charge which is possessed by both of them.
So, the outermost electrons were seven, and after addition of the electron, the number becomes eight, which is the required answer.

Note: The sodium chloride or the table salt is made up of sodium cation and chlorine anion. The outermost shell of the chlorine at ground state has seven electrons, and after the gain of one electron it attains a stable octet configuration.