The formula H₂O shows that water is made from two atoms of hydrogen (H) bonded to one atom of oxygen (O). Katie: Time for some science. And today it's a chemistry classic, the periodic table.

We know this because the hydrogen symbol has a subscript three after it, whereas the nitrogen symbol has no number meaning there’s only one. Chemical reactions can be represented using symbol ...

118 Elements and Their Symbols and Atomic Numbers ... which increase sequentially from 1 (Hydrogen) to 118 (Oganesson). Each element has unique chemical properties and is fundamental to ...