The matter that surrounds us, water, air, or even living beings, is made up of atoms, particles invisible to the naked eye. Atoms are composed of a nucleus, around which electrons orbit.
Inside the atom's nucleus are particles called neutrons, which are bound to protons. The cumulative number of protons and neutrons (together known as nucleons) in an atomic nucleus is the atomic mass of the atom.
When we talk about an isotope, we distinguish a type of atom that has the same number of protons but a different number of neutrons.
Inside the atomic nucleus, the number of protons defines the chemical properties of the atom. Two atoms with the same number of protons are called isotopes. They belong to the same chemical element because they have the same
number of protons in the nucleus.
However, isotopes, which belong to the same chemical element, are distinguished by different physical properties because of the number of neutrons they have. The neutron is an elementary particle of neutral electric charge, which can be stable or unstable.
Each isotope of the same chemical element thus shares the same atomic number (Z), which corresponds to the number of protons they have.
However, they are distinguished from each other by their atomic mass number (neutrons + protons); the number of neutrons they have is different.
In the notation of carbon 14, we therefore write 14
6 C, C being the chemical symbol of carbon, 14 its atomic mass number (protons + neutrons) and 6 corresponds to its atomic number, i.e. its number of protons.
Did you know?
Carbon-14 is an isotope used for dating objects and living materials in archeology.
Did you know?
The baseball team in the animated series The Simpsons is called “The Isotopes”. A nod to their sponsor, the Springfield nuclear power plant.