Answer: Two chlorine atoms
Explanation:
Chlorine is a nonmetal belonging to group 7 of the periodic table. It has an atomic number of 17 distributed as (2, 8, 7), so it has 7 valence electrons and needs JUST ONE to complete its outermost shell.
Cl + e- ---> Cl-
On the other hand, barium is a metal belonging to group 2 on the periodic table. It has an atomic number of 56 with 2
valence electrons in its outermost shell, and gives off the two electrons to form a stable octet structure.
Ba ----> Ba2+ + 2e-
Thus, barium loses its 2 outermost electrons to form a Ba2+ ion, while TWO chlorine atoms receive them to form 2Cl- resulting in an ionic bond in the compound, BaCl2 (Barium Chloride)
Ba2+ + 2Cl- ---> BaCl2
