As a chlorine atom becomes a negative ion, the atom blanks an electron

Answer: increases by

As a chlorine atom becomes a negative ion, the atom "increases by" an electron

Explanation:

Chlorine atom has an atomic number of 17, and an electronic configuration of 1s2, 2s2 2p6, 3s2 3p5 showing 7 valence electrons in its outermost shell.

Hence, it receives a single electron to achieve a stable octet structure with electronic configuration of

1s2, 2s2 2p6, 3s2 3p6. Therefore, Cl - is a univalent negative ion with 8 valence electrons in its outermost shell. The increase is shown below

Cl + e - - -> Cl-

Thus, as a chlorine atom becomes a negative ion, the atom "increases by" an electron