Isotopes differ in what property?

Isotopes differ in what property?

• A. Mass number (nuclear mass)
• B. Atomic number
• C. Electron configuration
• D. Chemical identity

Answer: (A)

Isotopes differ in the number of neutrons, which changes the mass number. The number of protons stays the same, so the atomic number—and thus the element’s identity and the basic electron count that sets the electron configuration—are unchanged. Because the mass number equals protons plus neutrons, swapping neutrons changes the nuclear mass while leaving the chemical behavior largely the same. A practical example is carbon-12 and carbon-14: both have six protons, so they’re the same element with the same chemistry, but different numbers of neutrons give them different mass numbers and different nuclear properties, like radioactivity in carbon-14. Hence, isotopes differ in their mass number.

Isotopes differ in the number of neutrons, which changes the mass number. The number of protons stays the same, so the atomic number—and thus the element’s identity and the basic electron count that sets the electron configuration—are unchanged. Because the mass number equals protons plus neutrons, swapping neutrons changes the nuclear mass while leaving the chemical behavior largely the same. A practical example is carbon-12 and carbon-14: both have six protons, so they’re the same element with the same chemistry, but different numbers of neutrons give them different mass numbers and different nuclear properties, like radioactivity in carbon-14. Hence, isotopes differ in their mass number.