What do they all mean? And what is the table actually used for? Dr. Tim: So this is the periodic table and each letter on it represents a different element. We call these letters symbols.

It is this structure that makes it very useful to scientists. All element symbols start with a capital letter, but when a symbol has 2 letters in it the second letter is always lower case.

Atomic number: The number of protons in the nucleus of an atom of the element. These rules help in identifying and writing chemical symbols consistently across all elements. The symbol serves as a ...