Answer:
The element A is S (sulfur)
Explanation:
The elements for the 3erd period in the periodic table are Na, Mg, Al, Si, P, S, Cl and Ar.
The one that has 6 e⁻ in its valence shell is the S, because it is missing 2 e⁻ to reach the octet rule. 2 e⁻ to has the most stable noble gas conformation.
The IE of S = 3360 kJ/mol
It is a little lower than Cl because the electron is so far from the nucleus, that's why we have to apply a very low ionization energy to rip the electron off.