SolutionsCovalent Structures
1. The cyanide ion
Write the Lewis structure of the cyanide ion, CN−, and state which atom bears the charge.
Electrons: 4 + 5 + 1 (for the charge) = 10 (5 pairs). [:C≡N:]−, with an unshared pair on each atom. Carbon owns 2 + 3 = 5 electrons, one more than its four: the negative charge is on carbon.
2. The ammonium ion
Calculate the formal charge on nitrogen in the ammonium ion, NH4+.
Nitrogen forms four bonds and has no unshared pairs: it owns 4 electrons (half of the 8 shared ones), one fewer than its five valence electrons. Its formal charge is +1.