Atomic Number

The atomic number is the number of Protons in an Atom.

• Carbon has six protons.
• Hydrogen has one proton.
• Oxygen has eight protons.

You will see these numbers (6,1,8) on the Periodic Table because it is the number that determines what the element is.

You may have heard of Carbon 14. Carbon typically has six protons and six neutrons, and is thus called Carbon-12 since 6+6=12. Carbon-14 has two additional neutrons.

Carbon-12 and Carbon-14 are Isotopes, atoms that different in Atomic Weight but have the same Atomic Number.