What atom could have the electron configuration of #1s^2 2s^2 2p^3#?
This is apparently a ground state configuration and the atom is neutral. There are a total of seven electrons, and in a neutral atom this means there are a total of seven protons. The number of protons is the atomic number. So, if you look on the periodic table, you will see that the element with the atomic number of 7 is nitrogen.