$A$ chlorine atom is electrically neutral,but a chloride ion is a charged ion. Explain.

(N/A) In a chlorine atom,the number of electrons is equal to the number of protons,which is $17$; hence,it is electrically neutral.
In a chloride ion,one electron is gained in the valence shell to attain a stable octet configuration. Consequently,the number of protons remains $17$,but the number of electrons becomes $18$ $(17 + 1)$. Since there is one excess electron compared to the number of protons,it carries a net charge of $-1$ and is thus negatively charged.