Nuclear Decay Product Calculator
What a nuclide becomes, for every decay mode.
Work out Nuclear Decay Product. What a nuclide becomes, for every decay mode. Free, with no account and nothing to download.
Protons plus neutrons. Uranium-238 is Z = 92, A = 238.
Daughter nuclide
Th-234
Thorium, Z = 90 · emits ⁴₂He (alpha particle)
The nucleus ejects a helium nucleus, losing two protons and two neutrons. Both the mass number and the charge are conserved across the arrow, and that conservation is the whole of the bookkeeping. Beta-minus decay is the one that catches people out: the nucleus emits a negative particle and its atomic number goes UP, because what actually happened inside was a neutron turning into a proton. The electron is a product of that conversion, not something that was sitting there. Beta-plus decay and electron capture produce the same daughter by different routes, which is why many nuclides do both.
How the Nuclear Decay Product Calculator works
Pick a parent nuclide and a decay mode to get the daughter, with the changes in atomic and mass number laid out. Beta-minus is the one worth watching: the nucleus emits a negative particle and its atomic number goes up, because a neutron turned into a proton.
Also known as: alpha decay calculator · beta decay calculator · daughter nuclide calculator · radioactive decay equation calculator
Frequently asked questions
What happens in alpha decay?
The nucleus ejects a helium-4 nucleus, losing two protons and two neutrons. The atomic number drops by 2 and the mass number by 4 — uranium-238 becomes thorium-234.
Why does beta-minus decay increase the atomic number?
Because a neutron converts into a proton, emitting an electron and an antineutrino in the process. The electron was not sitting in the nucleus beforehand; it is a product of the conversion. Carbon-14 becomes nitrogen-14.
What is the difference between beta-plus decay and electron capture?
Both turn a proton into a neutron and give the same daughter. Beta-plus emits a positron; electron capture absorbs an inner-shell electron instead. Many nuclides do both, in a fixed ratio.
Does gamma emission change the element?
No. Gamma decay only drops the nucleus from an excited state to a lower one, so both the atomic number and the mass number are unchanged. It usually follows another decay that left the daughter excited.
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