Lesson 3Beginner~6 min

Neutrons and Isotopes

Same element, different mass: how neutron count creates isotopes like carbon-12 and carbon-14.

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Concept

Same element, different mass

Protons define the element — but neutrons are more flexible. Two atoms can both be carbon (6 protons each) yet carry different numbers of neutrons.

These variants are called isotopes: same element, same chemistry, different mass.