Se
Reactive nonmetal
Selenium
Z 34A 79mass 78.971
Slow-motion stage
Selenium-79
proton
neutron
electron (β⁻)
Parent nucleus · 79 nucleons
34 protons (coral) and 45 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
7934Se7935Br+β⁻+ ν̄
A neutron turns into a proton. An electron and an antineutrino fly out.
Z
3435
+1
A
7979
no change
n⁰
4544
-1
Energy released
0.900MeVtypical value
Electron (max)0.900 MeV
Mass convertedE = Δm c²0.00097 u
In joules1.44 × 10-13 J
Compared with a bonda C–C bond is 3.6 eV≈ 250,000 ×
Measured beta energies fall between 0.02 and 3 MeV.
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