R

Radioactive Decay

Rate = k × [A]^m (half-life: t½ = 0.693/k for first order)
Quick Reference
Formula / NotationRate = k × [A]^m (half-life: t½ = 0.693/k for first order)
Also Known AsRadioactive disintegration, Nuclear decay, Transmutation

What is Radioactive Decay?

The spontaneous transformation of an unstable atomic nucleus into a more stable configuration by emitting particles or radiation. Types include alpha decay (α particle emission), beta decay (electron or positron emission), and gamma decay (photon emission). Follows first-order kinetics.

Formula & Notation

Rate = k × [A]^m (half-life: t½ = 0.693/k for first order)

Other Names / Synonyms: Radioactive disintegration, Nuclear decay, Transmutation

Properties & Characteristics

Types: α-decay (loses ²He nucleus, A−4, Z−2), β⁻ decay (neutron → proton + electron + antineutrino, Z+1), β⁺ decay (proton → neutron + positron + neutrino, Z−1), electron capture (K-capture, Z−1), γ-decay (energy release from excited nucleus, no A or Z change). First-order kinetics: N(t) = N₀ × e^(−λt). Half-life t½ = ln2/λ = 0.693/λ. Activity A = λN (measured in Becquerels or Curies).

Uses & Applications

Nuclear medicine: I-131 thyroid treatment, Tc-99m imaging, I-125 cancer brachytherapy. Radiometric dating: C-14 (archaeological, up to 50,000 yr), U-238 (geological, billions yr). Nuclear power generation (U-235 fission, Pu-239). Industrial: thickness gauges, sterilization of medical equipment by gamma radiation. Research: radiotracers in metabolism studies.

Safety Information

Ionizing radiation damages DNA, increasing cancer risk. Alpha particles (stopped by paper/skin, dangerous if inhaled/ingested). Beta particles (stopped by aluminum or plastic). Gamma rays require lead or concrete shielding. Cumulative dose limits: workers < 50 mSv/year, public < 1 mSv/year. Radioactive materials require specialized storage, handling, and disposal under regulatory licenses.

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

Key Facts

Term Radioactive Decay
Formula Rate = k × [A]^m (half-life: t½ = 0.693/k for first order)
Synonyms Radioactive disintegration, Nuclear decay, Transmutation

Frequently Asked Questions

The spontaneous transformation of an unstable atomic nucleus into a more stable configuration by emitting particles or radiation. Types include alpha decay (α particle emission), beta decay (electron or positron emission), and gamma decay (photon emission). Follows first-order kinetics.

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