Step-by-step explanation:
We have to write the electron configuration of Silicon. The atomic number of Si is 14, that means that it has 14 protons (the atomic number is equal to the number of protons of an element). Since the atom is neutrally charged, in this case it is also equal to the number of electrons.
atomic number = n° of protons = n° of electrons = 14
n° of electrons = 14
To write the electron configuration of Si we will have to arrange 14 electrons in the different sublevels. To write the electron configuration we have to place the electrons in a determined order. That order is given by the following image.
This is called the "diagonal rule", to fill the sublevels in the correct order we have to follow the arrows. We start with 1s, then 2s, 2p, 3s, 3p, 4s, 3d, 4p and so on.
In the sublevel s we can place up to 2 electrons, in the sublevel p we can place up to 6 electrons, in the sublevel p 10 electrons and in the sublevel f 14.
s ----> 2 p ----> 6 d ---> 10 p -----> 14
We start with the sublevel 1s and we place two electrons there. Then with the sublevel 2s with two more. then in the 2p we can place 6 electrons. The next one in 3s and we can place 2 electrons there. We have 1s2 2s2 2p6 3s2, we have placed 12, but we needed 14 so the last two will go to 3p. The electron configuration will be:
[Si] = 1s2 2s2 2p6 3s2 3p2
If we look at the periodic table we will see that the noble gas that is closest to Silicon is Neon. The atomic number of Ne is 10. That means that Ne has 10 protons and 10 electrons. So we can replace the first ten 10 electrons of our electron configuration by the electron configuration of Ne.
[Si] = [Ne] 3s2 3p2
Answer: A) [Ne] 3s2 3p2