What is the noble gas shorthand of silicon?
The full electron configuration of silicon is
Now look at the periodic table and find the noble gas at the end of the period the same as the number of filled shells. The noble gas at the end of Period 2 is neon, Ne.
If you replace all of the electron configuration for the filled shells with the noble gas's symbol, which is in square brackets, you get to the answer at the top of the page.
Note: When you get to the transition elements, you will have unfilled d-sub shell electrons to take into account. These need showing explicitly.