11.1.4—Isotopes are forms of the same element with different numbers of neutrons in
- Syllabus
- 9702–2028–2029
- Objective
- 11.1.4
- Level
- AS
Isotopes are atoms of the same element with different neutron numbers
Isotopes have the same proton number but different numbers of neutrons, so they share chemical identity but differ in mass and nuclear properties.
Compare Z first, then A. Isotopic abundance affects relative atomic mass without changing the element symbol.
Carbon-12 and carbon-14 both have Z=6; carbon-14 has two more neutrons and is radioactive.
Isotopes are not different elements, and isotope differences are not caused by different electron counts in neutral atoms.
ConceptA-Level CAIE Physics AS