Half Life — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

What is Half Life?

Half-life (t₁/₂) is the time required for half of a given quantity of a substance to undergo a specific process, most commonly radioactive decay or a first-order chemical reaction. For radioactive isotopes, the half-life is a characteristic constant independent of the initial amount or external conditions such as temperature and pressure. Half-life values range from fractions of a second for highly unstable nuclei to billions of years for stable isotopes, and are widely used in radiometric dating.

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What is Half Life?

Half-life (t₁/₂) is the time required for half of a given quantity of a substance to undergo a specific process, most commonly radioactive decay or a first-order chemical reaction. For radioactive isotopes, the half-life is a characteristic constant independent of the initial amount or external conditions such as temperature and pressure. Half-life values range from fractions of a second for highly unstable nuclei to billions of years for stable isotopes, and are widely used in radiometric dating.

More "H" Terms

Haber Process N₂ + 3H₂ ⇌ 2NH₃ | ΔH = −92 kJ/mol Hafnium Hf Half Cell Half-Cell E = E° − (RT/nF)lnQ Half-Life A(t) = A₀e^(−λt); t½ = ln2/λ Half-Reaction Halide X⁻ (e.g., F⁻, Cl⁻, Br⁻, I⁻) Halogen F₂, Cl₂, Br₂, I₂, At; Group 17; ns²np⁵ valence configuration Halogenation C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway Halogens Hard Acid Hard acid: small, highly charged, low polarisability (e.g., H⁺, Mg²⁺, Al³⁺) Hard Base Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O)

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