How do isotopes of an element differ?

Isotopes of an element differ in the number of neutrons they have in their nucleus.

Isotopes are variants of a particular chemical element. While all isotopes of an element share the same number of protons, they differ in the number of neutrons within the atomic nucleus. This difference in neutron number results in different atomic masses for the isotopes of the same element.

For example, consider the element carbon. It has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. All three isotopes have six protons because the atomic number, which defines an element, for carbon is six. However, carbon-12 has six neutrons, carbon-13 has seven neutrons, and carbon-14 has eight neutrons. This difference in the number of neutrons gives these isotopes different atomic masses: 12, 13, and 14 atomic mass units respectively.

The presence of different isotopes can significantly affect the properties of an element. For instance, carbon-12 and carbon-13 are stable, but carbon-14 is radioactive and decays over time, which is why it is used in radiocarbon dating.

In addition, isotopes can also influence the physical properties of an element. For example, heavy water, which contains the hydrogen isotope deuterium instead of the common isotope protium, freezes at a higher temperature than regular water.

In summary, isotopes of an element have the same number of protons but differ in the number of neutrons, leading to different atomic masses and potentially different physical and chemical properties. Understanding isotopes is crucial in many fields of science, including chemistry, physics, geology, and biology.