Answer:
Step-by-step explanation:
Before we write the electronic configuration, we need to know the number of electrons that the neytral atom of silicon has
Silicon has an atomic number of 14. What that means is that the number of protons in its nucleus is 14
For a neutral atom, the number of electrons is same as the number of protons. This is in place so as to preserve the electronic neutrality of the said neutral atom
For anionic silicon with a charge of -1, it means that the silicon atom has received an extra electron, and that brings the total count of electrons it has to 15
This means anionic silicon has the electronic configuration of neutral phosphorus since they have the same number of electrons
Finally, we can write the electronic configuration in the expanded form as follows: