What are isotopes? Give its two applications.

Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

Applications of isotopes:

1. Medical Applications: Radioactive isotopes are commonly used in medicine for diagnostic and treatment purposes. For example, the isotope Iodine-131 is frequently used to treat thyroid cancer. It's also used in imaging tests to help identify medical conditions and to monitor the body's response to treatment.

2. Archaeological Applications: Isotopes are used in dating archaeological finds. Carbon-14, a radioactive isotope, is used in carbon dating to determine the age of ancient artifacts and fossils.