What element is represented by #[Ar]4s^2 3d^10 4p^1#?
If you look up the element argon, Ar, on the periodic table, you will see that its atomic number is 18, which means that it has 18 protons in its atomic nuclei. In a neutral atom, the numbers of protons and electrons are equal. So a neutral Ar atom has 18 electrons. Therefore, the symbol