Question

How many valence electrons does an atom of Al possess?

Answer 1

Hint: As we know that valence electrons are the electrons that are present in the outermost shell of an atom. If we have to find the valence electrons, then we must have to know the atomic number of that atom. We can use atomic numbers to write the electronic configuration and then find the electrons in the valence shell.

Complete answer:
- We should understand the meaning of the term valence. It is basically the electrons in the valence shell of an atom called valence electrons.
- As we know that the atomic number of aluminium is 13, and its electronic configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^1$ . And it is found that the first 10 electrons are filled in the first and the second shells. And this leaves only three electrons in the third shell that is $3s^{2}3p^1$.
- So, we get total valence electrons in aluminium as the 13 - 10 = 3.
- From the above discussion we can understand that aluminium is having three electrons in its valence shell that makes it valence electrons. Hence, in this way we can calculate the number of valence electrons in aluminium.

Note: As we know that valency is the combining power of an element. It is found that elements in the same group have the same valence in the periodic table. Basically the valence of an element is related to the electrons that are present in the outer shell.