Predict the empirical formula of the compound formed by each of the following pairs of elements.a) Li,S b) Na,H c) Al,l d) Ca,O

1 answer

Look at the periodic table.
Li is in I so it has a valence of +1. S is in group VI (or 16 depending upon the system you are using) and it has a valence of -2; therefore, the formula is Li2S (Note that Li at +1 each is +2 total and that is neutralized by the -2 for S). Compounds must be zero.
Na is in group I BUT it is also in group VII on my chart( meaning it can have a valence of +1, which is the most usual, but it also can have -1 so the formula is NaH. Now you try the others.