Butane gas reacts with oxygen gas to give carbon dioxide gas and water vapor (gas). If you mix butane and oxygen in the correct
stoichiometric ratio, and if the total pressure of the mixture is 392 mmHg, what is the pressure (in mmHg) of water vapor after the reaction has completed (temperature and volume do not change).
beacause all the elements in period 3 has different valence electrons hence you look at the first element in period 3 is sodium which has a valence electron of 1 when you go across the period to the right their valence electron decreases to be negative