Which term best describes atoms of the same element with different numbers of neutrons?

Which term best describes atoms of the same element with different numbers of neutrons?

• A. Ion
• B. Atom
• C. Isomer
• D. Isotope

Answer: (D)

Atoms of the same element with different numbers of neutrons are called isotopes. The defining feature is that they share the same number of protons, so they are the same element, but they differ in mass because the neutron counts vary. Chemically, isotopes behave very similarly since chemical behavior depends mainly on electron interactions governed by the atomic number, but their physical properties and nuclear stability can differ. For example, carbon-12 and carbon-14 are both carbon, yet carbon-14 is radioactive. Why the other terms don’t fit as well: an ion is a charged version of an atom, defined by electron loss or gain rather than neutron count; an atom is any single unit of an element and doesn’t specify neutron variation; an isomer refers to different structural arrangements or configurations, not differences in neutron number.

Atoms of the same element with different numbers of neutrons are called isotopes. The defining feature is that they share the same number of protons, so they are the same element, but they differ in mass because the neutron counts vary. Chemically, isotopes behave very similarly since chemical behavior depends mainly on electron interactions governed by the atomic number, but their physical properties and nuclear stability can differ. For example, carbon-12 and carbon-14 are both carbon, yet carbon-14 is radioactive.

Why the other terms don’t fit as well: an ion is a charged version of an atom, defined by electron loss or gain rather than neutron count; an atom is any single unit of an element and doesn’t specify neutron variation; an isomer refers to different structural arrangements or configurations, not differences in neutron number.