The atoms of different elements having the same number of neutrons but different number of protons are called as which of the following?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Isotones
Isotones are atoms of different elements that have the same number of neutrons but different numbers of protons. Carbon-14 (6 protons, 8 neutrons), nitrogen-15 (7 protons, 8 neutrons) and oxygen-16 (8 protons, 8 neutrons) are isotones: each has 8 neutrons.
Why the other options are incorrect
Option (1) Isobars — Incorrect. Atoms of different elements with the same mass number, such as argon-40 and calcium-40.
Option (3) Isotopes — Incorrect. Atoms of the same element (same number of protons) with different numbers of neutrons, such as carbon-12 and carbon-14.
Option (4) Isoelectronic — Incorrect. Atoms or ions with the same number of electrons, such as Na+, Mg2+ and Ne (10 electrons each).
Tip: One letter in each name tells what stays the same: isotopes have the same protons, isotones the same neutrons, and isobars the same atomic mass number.