Some things you need to know: 1. formulae are case sensitive while names are not 2. when typing formulae just type the characters(english letters and numbers) from left to right order, you don't need to care about their position. 3. in cations, all numbers are on upper hand side except NH4+, which is on lower hand side 4. in anions, numbers of -1 charge ions are on lower hand side; if there are more than one numbers in -2 charge ions, the last number is on the upper hand side while the others are on lower hand side; PO43- the 4 is lower hand side.
