F
Halogen

Fluorine

Z 9A 19mass 18.998

Slow-motion stage

Fluorine-19

proton
neutron
electron (β⁻)

Parent nucleus · 19 nucleons

9 protons (coral) and 10 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

199F1910Ne+β⁻+ ν̄

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

Z
910
+1
A
1919
no change
n⁰
109
-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