Consider the Lewis structure for the polyatomic oxyanion shown here, where X is an element from the third period (Na−Ar). By changing the overall charge, n, from 1- to 2- to 3- we get three different polyatomic ions. a) For each of these ions identify the central atom, X. Arrange your answers in order increasing n. Express your answer as a chemical symbols separated by commas.

b) For each of these ions determine the formal charge of the central atom, X. Arrange your answers in order increasing n. Express your answer as a signed integer separated by commas.

c) For each of these ions draw a Lewis structure that makes the formal charge on the central atom equal to zero. Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all lone pairs of electrons. Use square brackets to denote the overall charge.