How are isotopes different from their neutral atoms?

Question

They differ in the number of neutrons.

They differ in the number of protons.

They differ in the number of electrons.

The number of protons, neutrons, and electrons are all halved.

Answer 1

The first option is correct: isotopes differ from their neutral atoms in the number of neutrons. The number of protons remains the same, as this determines the element, while the difference in neutron number results in different atomic masses for isotopes of the same element. The number of electrons may vary in ions, but not in isotopes. The last option, where the number of protons, neutrons, and electrons are all halved, is not accurate as isotopes typically differ only in their neutron number, not in the number of protons or electrons.