Carbon-12 is the most common isotope of carbon, with 6 protons and 6 neutrons in its nucleus.
Carbon-12 cheat sheet for homework
Variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.
The number of protons found in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
The central part of an atom that contains protons and neutrons.