Which statement about isotopes is true?

Which statement about isotopes is true?

• A. Isotopes are atoms with different numbers of protons.
• B. Isotopes are variants of an element that have the same number of protons but different numbers of neutrons.
• C. Isotopes are molecules with different bond types.
• D. Isotopes are ions with a net charge.

Answer: (B)

Isotopes are variants of the same element that have the same number of protons but different numbers of neutrons. The proton count fixes the element’s identity, so changing protons would produce a different element. Neutrons alter the nucleus’s mass and stability, so isotopes can differ in nuclear properties like radioactivity, while their chemistry stays very similar because the electrons experience essentially the same nuclear charge. For example, carbon-12 and carbon-14 both have six protons; carbon-12 has six neutrons, whereas carbon-14 has eight neutrons, making it radioactive. The other statements mix up nuclear composition with charge or bonding, which is not what defines isotopes.

Isotopes are variants of the same element that have the same number of protons but different numbers of neutrons. The proton count fixes the element’s identity, so changing protons would produce a different element. Neutrons alter the nucleus’s mass and stability, so isotopes can differ in nuclear properties like radioactivity, while their chemistry stays very similar because the electrons experience essentially the same nuclear charge. For example, carbon-12 and carbon-14 both have six protons; carbon-12 has six neutrons, whereas carbon-14 has eight neutrons, making it radioactive. The other statements mix up nuclear composition with charge or bonding, which is not what defines isotopes.