* Mass Number: The mass number represents the total number of protons and neutrons in an atom's nucleus.
* Protons: All sodium atoms have 11 protons. This is what defines them as sodium.
* Neutrons: The difference in mass number comes from the neutrons.
* A sodium atom with a mass number of 22 has 11 neutrons (22 - 11 = 11).
* A sodium atom with a mass number of 24 has 13 neutrons (24 - 11 = 13).
In summary:
* Both atoms are sodium because they have 11 protons.
* The atom with a mass number of 24 has two extra neutrons compared to the atom with a mass number of 22.
These are called isotopes - atoms of the same element with different numbers of neutrons. Isotopes have the same chemical properties but slightly different physical properties due to their different masses.
