Chemistry

Nuclear chemistry

Radioactivity, half-life, binding energy.

Basics

Decay types

Alpha: a He nucleus. Beta: neutron ↔ proton + e±. Gamma: a high-energy photon. Stability depends on the n/p ratio and shells. Intensity roughly falls with distance squared.

Mass defect

A nucleus weighs less than its free nucleons. The defect times c² is binding energy. Near iron, binding per nucleon peaks, so fusion of lights and fission of heavies both release energy.

Formulas

Radioactive decay

N = N₀ e^{−λ t}, t_{1/2} = ln 2 / λ

Remaining nuclei. Activity A = λ N.

Symbols

  • λ decay constant
  • t_{1/2} half-life

Binding energy

E_b = Δm c²

Mass defect Δm. Often quoted in MeV.

Symbols

  • Δm mass defect

In this field