Isotope, Isotone & Isobar

Isotope, Isotone & Isobar

In atomic science, atoms are compared based on their number of protons , neutrons, and mass numbers. Three important terms that describe such comparisons are Isotopes, Isotones, and Isobars.

1. Isotopes

Definition: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons . This means their mass numbers are different.

Example:

• Protium (¹H): 1 proton, 0 neutrons
• Deuterium (²H): 1 proton, 1 neutron
• Tritium (³H): 1 proton, 2 neutrons

Each of these is a hydrogen atom since they all contain one proton, but their masses differ because the number of neutrons is not the same.

2. Isotones

Definition: Isotones are atoms of different elements that have the same number of neutrons, but different numbers of protons.

Example:

• Carbon-14 (₆¹⁴C): Contains 6 protons and 8 neutrons
• Nitrogen-15 (₇¹⁵N): Contains 7 protons and 8 neutrons

These atoms belong to different elements but share the same neutron number.

3. Isobars

Definition: Isobars are atoms belonging to different elements that share the same mass number but have different counts of protons and neutrons.

Example:

• Argon-40 (₁₈⁴⁰Ar): 18 protons, 22 neutrons
• Calcium-40 (₂₀⁴⁰Ca): 20 protons, 20 neutrons

Even though the elements are different, their total mass number is the same.

Summary Table