text: Count the number of valence electrons in each atom, and add them up. Cl = 7, O = 6, so total is 19. Chlorite (ClO2-) is an ion with a minus 1 charge, so add another electron to the count for that extra one. 20 total.\n\nNow, arrange the atoms and draw in bonds until each atom has a full octet.\n\nO-Cl-O with six dots around each O, and four dots around the Cl.\n\nThe formal charge on this molecule works out fairly nicely too, but if you haven't gotten to formal charges yet, then don't worry about it.