The number of protons is what defines the element. Oxygen, for example, has eight protons. However, the number of neutrons in ...

When two hydrogen atoms and an oxygen atom get close enough, the electron from each atom feels an attraction from the protons in the other atom's nucleus. This attraction pulls the atoms together. The ...

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.