As
Metalloid

Arsenic

Z 33A 75mass 74.922

Slow-motion stage

Arsenic-75

proton
neutron
electron (β⁻)

Parent nucleus · 75 nucleons

33 protons (coral) and 42 neutrons (blue) are packed together and held by the strong force.

illustrative nucleus

A real decay takes about 10⁻²¹ s. At ⅓× this stage stretches it across eleven seconds.

Choose a reaction

Reaction

7533As7534Se+β⁻+ ν̄

A neutron turns into a proton. An electron and an antineutrino fly out.

Z
3334
+1
A
7575
no change
n⁰
4241
-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