Question

What element has the electron configuration `1s^2 2s^2 2p^6 3s^2 3p^3`?

Answer 1

If there are `15` `"electrons"` in the neutral atom.....

Explanation:

There must be also `15` `"protons"` in the element's nucleus. And thus if `Z=15`, the element must be `"phosphorus"`.

What about the configuration: `1s^(2)2s^(2)2p^(6)3s^(2)3p^5`?