Which of the following accurately describes properties of valence? a. nonmetallic elements tend to have a positive valence and tend to be electron borrowers. b. metals tend to have a negative valence and tend to be electron borrowers. c. the greater the number of electrons an atom has to borrow or to lend, the greater the activity of the atom. d. the smaller the number of electrons an atom has to borrow or to lend, the greater the activity of the atom