Quick Answer:The Isotopes of Hydrogen Model sets out the three isotopes of hydrogen side by side: protium with 1 proton and 0 neutrons, deuterium with 1 proton and 1 neutron, and tritium with 1 proton and 2 neutrons.
Last updated: 19 October 2026
Key Features
Three separate isotope models for direct comparison.
Each nucleus has one proton; only the neutron count changes.
Electron markers complete each atom.
Explains why isotopes share an atomic number but differ in mass number.
Technical Specifications
Specification
Value
Isotopes shown
Protium, deuterium, tritium
Protium
1 proton, 0 neutrons
Deuterium
1 proton, 1 neutron
Tritium
1 proton, 2 neutrons
Components
Three isotope models, nucleus representation, electron markers
How It Is Used
Students count the protons, neutrons and electrons in each of the three models and note what stays the same and what changes. The teacher uses the comparison to define isotopes, atomic number and mass number, ideally with a periodic table to hand, for middle and secondary school classes.
Frequently Asked Questions
How do the three atoms in the Isotopes of Hydrogen Model differ?
All three have 1 proton, so the atomic number is the same. Protium has 0 neutrons, deuterium 1 and tritium 2, so their masses differ.
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