Question

How many valence electrons are present in sodium with atomic number 11?

Answer 1

Hint: To start with this question, we should be well versed with the terms like valence electrons, valency, electronic configuration, atomic number , filling the shells with $ {e^ - } $ and a brief idea about sub-shells( if we consider this from class11 point of view).

Complete step by step answer:
As mentioned above, let us learn about these terms.
Atomic number: It determines the place or position of an element in the periodic table. It is defined as the number of protons present in the nucleus of an atom.
Electronic configuration: we can define it as the distribution of $ {e^ - } $ of an atom in the orbital.
Valence electrons: $ {e^ - } $ of the outermost shell that are available to make the bond with the readily available atom/ion. The bond can be covalent or ionic by nature, depending on the elements taken into consideration.
Valency: it is the combining capacity of the element with other atoms when it forms molecules or compounds.
Sodium has an atomic number 11 and symbol $ Na $ . It has electronic configuration of 2, 8and 1. In another format, we write it as $ 1{s^2}2{s^2}2{p^6}3{s^1} $ where $ s $ and $ p $ are the sub shells. 2,8,1 means 2 $ {e^ - } $ will be in the innermost shell K, 8 in the shell L and 1 in shell M. since it is easy for $ Na $ to donate one $ {e^ - } $ of the outermost shell to attain the stable configuration of noble gas. So it is willing to lose an $ {e^ - } $ from shell M.
Hence the valence $ {e^ - } $ in case of $ Na $ is 1.

Note:
 $ Na $ is kept in kerosene because when it is kept in air, it absorbs moisture and catches fire. Thus it is advised in the labs not to touch the sodium pellets with bare hands. Also, it is one of the important metals as it can react with water, snow and ice to give sodium hydroxide and hydrogen.