16. representative elements are those found in the * a. s and p blocks b. d block c. s and d blocks d. d and f blocks 17. within the representative elements, atomic size generally * a. remains constant within a period b. increases as you move left to right across an energy level c. increases as you move down a group d. cannot be predicted 18. ions are charged particles formed from atoms. which of these would be true? * a. cations form when an atom gains electrons. b. cations form when an atom loses electrons. c. anions form when an atom gains protons. d. anions form when an atom loses protons.