Pick what you want to calculate — Half-Life (T½), Time Elapsed (t), Initial Quantity (N₀), or Remaining Quantity (N) — then fill in the other known values and your Time Unit to get your result alongside the Decay Constant (λ), Mean Lifetime (τ), and Percentage Remaining.
Result
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Decay Constant (λ)
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Mean Lifetime (τ)
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Percentage Remaining
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Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation. During this process, the nucleus transforms into a different element or isotope, releasing particles and energy in the form of radiation.
Half-life and decay constant are inversely related. The decay constant (λ) represents the probability of decay per unit time, while half-life (T½) is the time needed for half the sample to decay. They're related by: λ = ln(2)/T½.
Half-life is the time for half a sample to decay, while mean lifetime is the average time a particle exists before decaying. Mean lifetime (τ) equals 1/λ, where λ is the decay constant, and is about 1.44 times longer than the half-life.
Yes, this calculator works for any first-order decay process, including chemical reactions that follow exponential decay kinetics. It's commonly used for radioactive decay, drug metabolism, and certain chemical decomposition reactions.
Carbon-14 dating uses the radioactive decay of carbon-14 to determine the age of organic materials. Carbon-14 has a half-life of approximately 5,730 years, making it useful for dating materials up to about 50,000 years old.
Half-life calculations are very accurate when the decay follows first-order kinetics and measurement conditions are controlled. However, real-world factors like temperature, pressure, and sample purity can affect actual decay rates.