Carbon-12 and carbon-13 are isotopes of carbon. What does this mean?

Hello!

Each chemical element (and carbon among them) is defined by the number of protons in its nucleus. Also the same number of electrons are found in each atom of the same element.

For carbon, this number is 6, and it cannot be changed in a chemical reaction.

But neutrons may also be found in an atom (in its nucleus). Neutron has zero electrical charge and its mass is similar to the proton's mass. And many elements have representatives with a different number of neutrons. Classes of these representatives are called isotopes (of an element).

Carbon-12 has atomic mass 12, i.e. it has 6 neutrons to its 6 protons. Carbon-13 has 6 protons also and 7 neutrons. These carbon isotopes are the only two stable ones (there are many other isotopes of carbon, but they are radioactive).

Carbon-12 is the most abundant (almost 99%).

The chemical properties of these isotopes are the same.