What determines which element goes first? For example CO2. Why does carbon come first? Does it go by the order they are in on the periodic table? :confused:

Not necessarily. I don't know exactly why this is like that but I've noticed that the 'solid at room temperature pressure' elements ususlly come before. For instance, you burn solid carbon (the simplest example) in air (oxygen)to produce carbon dioxide.

There are also radicals, like oxide (dioxide, trioxide, etc), sulphate, sulphite, sulphide, nitrate, nitrite, nitride, chlorate, chloride, carbonate, etc which come after. There are a few exceptions though, like sodium ethanoate, where the ethanoate is usually put before the sodium, CH3COONa (CH3COO is ethanoate)