Question

How many electrons are there on the valence shell of an element with $12$ electrons?

Answer 1

To solve this question, first we have to find the total valence electrons in the given compound. Then according to the Octet Rule, check how many electrons are left and finally conclude the bond pairs and lone pairs. Then we will get the valence electrons present in the valence shell. The number of protons is equal to the atomic number.

Complete step-by-step answer:
From the time we are studying about the periodic table and the elements, we are concerned about the arrangement of electrons in atoms, the total number of electrons present in them and the number of valence electrons present. So that we will get an idea of the various oxidation states that an element can possess and various types of chemical reaction an element can undergo.

So, we are very familiar with the term valence shell or valence orbit; it is the outermost shell present in the atom. Hence we can say that the valence electron is the electrons present in the outermost shell of the electrons and these electrons are removed to obtain the octet configuration. The valence shell is the last shell which the element's electrons take up. (In this case Magnesium)

Valency is the number of the electrons present in the outermost shell of an atom which is also called the valence shell of an atom. Those electrons are important to be studied as they are the most loosely held electrons of the atoms. Magnesium is an atom with the atomic number $12.$ It comes right after sodium $Na.$

Electronic Configuration of Magnesium is given by: $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}$
Here $2$ in K shell, $8$ in L shell and $2$ in M shell. Thus electronic configuration is $2,8,2$ which sums up to $12.$

Therefore, $2$ electrons are there on the valence shell of an element with $12$ electrons.

Note: The only exception case for the standard is hydrogen, which is at its most minimal energy when it has two electrons in its valence shell. Helium is comparable in that it, as well, just has space for two electrons in its solitary valence shell. Hydrogen and helium have just a single electron shell.