Question

Neon has 10 protons and 10 electrons. How many additional electrons would it take to fill the outer (second) electron shell?

Answer 1

zero!

Explanation:

Neon is a noble gas. The noble gasses all have filled outer electron shells.

Put another way, the number of electrons that can be put in any shell is `2n^2` so, for the n=1 shell you get `2xx1^2` or 2 electrons. for the n=2 shell you get `2 xx 2^2` or eight electrons.

`2+8=10`

That's neon.