The number of protons plus the number of neutrons in an atom is equal to its atomic number
mass number
nuclear model
energy level

Ireally need ! calcium metal reacts with a potassium chloride solution to form calcium chloride and potassium ions. balance this reaction. (s) + (aq) → cacl2(s) + +(aq) a) 1, 2, 1, 2 b) 1, 2, 1, 1 c) 1, 1, 1, 1 d) 2, 1, 2, 1