Question

What is the Noble gas notation of silicon (Si) ?

[Ne] 2s22p2
[Ar] 3s23p2
[Ne] 3s23p2
[Mg] 3p2

Answer 1

Can you find the full electron configuration?

Answer 2

To identify the noble gas configuration, the easiest thing to do is to look at the periodic table. Find silicon (Si) and count back along the atomic numbers until you reach a Noble gas element. This is the element which we will place in the square brackets, making reference to its electronic configuration. The atomic number indicates the number of electrons an atom of the element has.

We then count back along the atomic numbers up to silicon to identify the number of s-electrons and p-electrons Si has in its outer or valence shell. This valence shell has a principal quantum number of n=3, and so the valence electrons will be placed into either 3s or 3p orbitals. The first two of these will go into the s-orbital, whilst any remainder will occupy the higher energy p-orbital. So, by counting along the third row in the periodic table up to silicon, you should be able to identify the electronic configuration. Good luck! :)