Isotope
Definition and meaning of Isotope in chemistry.
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Because they contain the same number of protons, isotopes share the same atomic number and therefore have virtually identical chemical properties.
In more detail
Since isotopes of an element have the same number of protons and electrons, they react the same way chemically; only their mass and nuclear stability differ. Many elements occur naturally as a mixture of isotopes, and the atomic mass shown on the periodic table is the weighted average of those isotopes. Some isotopes are stable, while unstable (radioactive) isotopes are used in applications such as carbon dating and medical imaging.
Key facts
| Same | Number of protons (atomic number) |
|---|---|
| Different | Number of neutrons (mass number) |
| Chemical properties | Essentially identical |
| Field | General chemistry |
Carbon-12 and carbon-14 are isotopes of carbon: both have 6 protons, but carbon-12 has 6 neutrons whereas carbon-14 has 8.
Frequently asked questions
Do isotopes have the same chemical properties?
Yes. Isotopes of an element have the same number of protons and electrons, so they behave the same chemically. They differ mainly in mass and in physical properties.
What is an example of an isotope?
Carbon has three natural isotopes: carbon-12, carbon-13, and carbon-14. All have 6 protons, but they have 6, 7, and 8 neutrons respectively.