Which term best describes variations of an element's atoms that differ in neutron number but share the same number of protons?

Which term best describes variations of an element's atoms that differ in neutron number but share the same number of protons?

• A. Isotope
• B. Hypothesis
• C. Ion
• D. Electron cloud model

Answer: (A)

Isotopes are variants of an element that share the same number of protons but differ in the number of neutrons. Protons determine the element’s identity, so all isotopes of an element have the same chemical behavior, while changes in neutron number alter the mass and stability. That’s why the term fits: it describes atoms of the same element with identical proton counts but different neutron counts. For example, carbon-12 and carbon-14 both have 6 protons, but carbon-12 has 6 neutrons while carbon-14 has 8 neutrons, leading to different masses and, in some cases, stability. The other terms don’t describe this situation: a hypothesis is a testable guess, an ion is an atom with a net electric charge from losing or gaining electrons, and the electron cloud model describes electron positions around the nucleus rather than differences in neutron number.

Isotopes are variants of an element that share the same number of protons but differ in the number of neutrons. Protons determine the element’s identity, so all isotopes of an element have the same chemical behavior, while changes in neutron number alter the mass and stability. That’s why the term fits: it describes atoms of the same element with identical proton counts but different neutron counts. For example, carbon-12 and carbon-14 both have 6 protons, but carbon-12 has 6 neutrons while carbon-14 has 8 neutrons, leading to different masses and, in some cases, stability. The other terms don’t describe this situation: a hypothesis is a testable guess, an ion is an atom with a net electric charge from losing or gaining electrons, and the electron cloud model describes electron positions around the nucleus rather than differences in neutron number.