* Atomic number: 6

* Atomic mass: 12.011 amu (atomic mass units)

Here's what those numbers mean:

* Atomic number: The number of protons in an atom's nucleus. This defines what element the atom is. All carbon atoms have 6 protons.

* Atomic mass: The average mass of all the isotopes of an element. Carbon has two common isotopes: Carbon-12 (6 protons and 6 neutrons) and Carbon-13 (6 protons and 7 neutrons). The atomic mass of 12.011 reflects the relative abundance of these isotopes.