Atomic Structure: Isotopes

Isotopes are versions of a particular element that have identical numbers of protons and electrons, but different numbers of neutrons.
The atomic number of an element, which represents the number of protons in an atom, is the same for all isotopes of a particular element. However, the atomic mass number, which is the sum of protons and neutrons, varies between isotopes.
For instance, Carbon-12, Carbon-13, and Carbon-14 are all isotopes of carbon. They all have 6 protons, but Carbon-12 has 6 neutrons, Carbon-13 has 7 neutrons, and Carbon-14 has 8 neutrons.
Isotopes behave the same way chemically, because their chemical properties are determined by the number of electrons and arrangement of electrons, which are the same in all isotopes of the same element.
However, isotopes can have different physical properties. For example, some isotopes are stable, while others are unstable and can undergo radioactive decay.
Unstable isotopes, or radioisotopes, can decay over time and emit radiation in the process. This process is used in a number of applications, such as in treating cancer (radiotherapy), dating archaeological samples (radiocarbon dating), and generating electricity in nuclear power plants.
The relative atomic mass of an element on the periodic table is an average value, taking into account the masses of the different isotopes and their relative abundances.
Isotopes can be detected and identified using a mass spectrometer, an instrument that separates isotopes based on their mass and charge.