Answer
See the answer below.
Work Step by Step
A: group 1, period 5
B: group 16, period 4
a) A is a metal from group 1 (alkaline).
b) B, ionization energy is bigger in later groups and earlier periods.
c) A, the negative of the electron attachment energy is bigger in later groups and earlier periods.
d) A, atomic radius is bigger in later periods and earlier groups.
e) A must lose one electron to have a noble gas configuration, B must gain two:
$A_2B$
