Well, instead of looking at the atomic number, you should look at the properties of elements in each column, and you will see similarities in properties. Like first row, other than hydrogen, all of them are metals and highly reactive. You do not want to put a chunk of sodium in water. Reactivity usually decreases in metals as it goes to the right. Also notice how nonmetals are all in the right side except hydrogen. The last row is non reactive. There are other things in the periodic table in which you can predict an element's properties. It is not exact, but there are patterns.