Fission, fusion and reaction energy
Nuclear rearrangement can release or require energy.
Key knowledge
Fission splits a nucleus into smaller products; fusion combines nuclei. Reaction Q = (Σm_initial − Σm_final)c² measures rest-energy release: Q > 0 is exothermic and Q < 0 requires energy input.
Values and equations
Q = (Σm_initial − Σm_final)c²
- Q
- Reaction rest-energy release J
- m_initial, m_final
- Participant rest masses under a consistent convention kg
- c
- Vacuum light speed m s⁻¹
Conditions and scope
- Include all reaction participants and use consistent nuclear or atomic mass accounting.
- Neither all fission nor all fusion reactions are exothermic; positive Q alone does not establish reaction rate or overcome barriers.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Samuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice University2 sources
Evidence and review
Nuclear splitting/combining definitions and rest-mass/binding-energy release examples.
2026-10-10 · Reaction definitions and Q balance only; reactor design, rates and numerical yields excluded.
Entry details
Permanent link to this entry ↗- Record identity
- physics-fission-fusion
- Revision
- university-reference.1
- Structured reference record
- University reference · University core expansion