M

Mass Defect

Δm = Z·mₚ + N·mₙ − m_nucleus
Quick Reference
Formula / NotationΔm = Z·mₚ + N·mₙ − m_nucleus
Also Known AsNuclear mass defect, binding energy mass equivalent, nuclear mass difference

What is Mass Defect?

Mass defect is the difference between the calculated mass of an atomic nucleus (sum of the masses of its component protons and neutrons) and the actual measured mass of that nucleus. The nucleus is lighter than the sum of its parts because some mass has been converted to binding energy (E = mc²) that holds the nucleus together. The binding energy per nucleon is a measure of nuclear stability.

Formula & Notation

Δm = Z·mₚ + N·mₙ − m_nucleus

Other Names / Synonyms: Nuclear mass defect, binding energy mass equivalent, nuclear mass difference

Properties & Characteristics

Δm = Z·mₚ + N·mₙ − m_nucleus. Binding energy: E_b = Δm·c². Fe-56 has highest binding energy per nucleon (~8.8 MeV/nucleon). Iron-peak stability explains fusion stops at Fe in stars. Mass defect for ¹H nucleus = 0 (by definition). Average binding energy: ~7–8 MeV/nucleon for stable nuclei.

Uses & Applications

Nuclear energy calculations (fission and fusion). Nuclear reactor design. Understanding stellar nucleosynthesis. Isotope production in nuclear physics. Mass spectrometry precision measurements. Nuclear medicine (radiopharmaceutical design). Particle physics research.

Safety Information

Nuclear processes involving mass defect: radiation hazards, criticality risk. Nuclear fission/fusion: extreme energy release. Radiation safety essential. Regulatory compliance for nuclear materials.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Mass Defect
Formula Δm = Z·mₚ + N·mₙ − m_nucleus
Synonyms Nuclear mass defect, binding energy mass equivalent, nuclear mass difference

Frequently Asked Questions

Mass defect is the difference between the calculated mass of an atomic nucleus (sum of the masses of its component protons and neutrons) and the actual measured mass of that nucleus. The nucleus is lighter than the sum of its parts because some mass has been converted to binding energy (E = mc²) that holds the nucleus together. The binding energy per nucleon is a measure of nuclear stability.

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