In this periodic table of elements quiz, you have 10 minutes to name as many elements as you can, given only their symbol ...

This is the chemical symbol for chlorine, written with its mass number and atomic number. Calculate the number of protons, neutrons and electrons an atom of chlorine contains. Number of protons ...

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.