How would you find the grams on the periodic table?
The periodic table doesn't show grams; and which grams ?
How would you predict where it would fit in the periodic table if you did not know it's atomic number?
To find the period of an element on the periodic table, you look at the end of the row and see what number is there. For example, if your were trying to find the period of Oxygen, you would look all the way to the right or left side of the table and see what number there is, and you would find that oxygen is in period 2.