Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is an isotope?

1. Atoms with identical numbers of protons and neutrons

2. Atoms of the same element with different numbers of neutrons

3. Atoms of different elements with the same atomic number

4. Atoms that have lost electrons and gained a charge

The correct answer is: Atoms of the same element with different numbers of neutrons

An isotope refers specifically to atoms of the same element that have the same number of protons but differ in the number of neutrons. This distinction in neutron count leads to variations in atomic mass, but because they are still the same element (having the same number of protons), they exhibit similar chemical properties. For example, carbon has several isotopes, including carbon-12, which has 6 neutrons, and carbon-14, which has 8 neutrons. These isotopes have different masses but are both chemically classified as carbon. This definition aligns precisely with the characteristics that define isotopes, making this understanding fundamental in fields like chemistry, nuclear physics, and various applications such as radiometric dating and medical imaging.