You may notice if we look at the atomic masses of elements in the periodic table that they are rarely ever whole numbers, just like for carbon where the atomic mass is 12.011.
This is because the atomic mass of carbon is based on the average atomic masses of its isotopes and the abundance of each isotope.
The numbers that are after the carbon refer to the atomic mass.
The most common and abundant isotope of carbon is carbon-12.
In a given element, the number of neutrons can be different from each other, while the number of protons is not.
Isotopes are atoms with the same number of protons but that have a different number of neutrons. As you can see, they have the same atomic number, or number of protons, (number at the lower left of the element) but different atomic masses (number at the upper left of the element).
The nucleus is made of protons and neutrons, and the electrons surround the nucleus, as shown in the illustration below.
The sum of the number of protons and the number of neutrons is equal to the atomic mass.
Since the atomic number is equal to the number of protons and the atomic mass is the sum of protons and neutrons, we can also say that isotopes are elements with the same atomic number but different mass numbers. The number of neutrons can be calculated by calculating the difference between the atomic mass and atomic number.
We can see that for the isotopes of hydrogen, they have varying number of neutrons.
These isotopes can help determine the chemical composition and age of minerals and other geologic objects.
Some examples of stable isotopes are isotopes of carbon, potassium, calcium and vanadium.
Free 5-day trial Not all atoms of an element are identical - atoms of the same element can have different numbers of neutrons.