Iwill award ! anwser its for a test what determines an atom's reactivity?
a) how many protons the atom contains.
b) how many energy levels the atom contains.
c) whether the atom is a metal or a nonmetal.
d) how many valence electrons the atom contains.

Explanation:

The number of electrons in the outermost shell of an atom determines its reactivity. Noble gases have low reactivity because they have full electron shells. Halogens are highly reactive because they readily gain an electron to fill their outermost shell.

Explanation: The number of electrons in the outermost shell of an atom determines its reactivity. Noble gases have low reactivity because they have full electron shells. Halogens are highly reactive because they readily gain an electron to fill their outermost shell.

So it b

the energy to form plasma comes from heat or electricity in the atmosphere!

sunny~ ☺

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.