work out how many atoms of each element are in the chemical formula add together the A r values for all the atoms of each element ...

Hence atomic number = 18 Number of protons + neutrons = 18 + 22 = 40. Hence mass number = 40The chemical ... the atoms it contains to write down its formula. For example, the formula for carbon ...

The chemical formula for water is H2O, which means this molecule has 3 atoms: 2 of hydrogen (H) and 1 oxygen (O) atom. Using the periodic table of the elements to find atomic weights, we find that ...