K
Alkali metal
Potassium
Z 19A 39mass 39.098
Slow-motion stage
Potassium-40
proton
neutron
electron (β⁻)
Parent nucleus · 40 nucleons
19 protons (coral) and 21 neutrons (blue) are packed together and held by the strong force.
A real decay takes about 10⁻²¹ s. At ⅓× this stage stretches it across eleven seconds.
Choose a reaction
Reaction
4019K4020Ca+β⁻+ ν̄
A neutron turns into a proton. An electron and an antineutrino fly out.
Z
1920
+1
A
4040
no change
n⁰
2120
-1
Energy released
1.31MeV
Electron (max)1.310 MeV
Mass convertedE = Δm c²0.00141 u
In joules2.10 × 10-13 J
Compared with a bonda C–C bond is 3.6 eV≈ 363,889 ×
Half-life of Potassium-40
1.25 billion years
One of the main sources of natural radioactivity in your body.
The particle
- Charge
- −1
- Mass
- 1/1836 u
- Speed
- Up to 99.9% of the speed of light
- Ionising power
- Moderate
- Stopped by
- A few millimetres of aluminium