Hg
Transition metal

Mercury

Z 80A 201mass 200.59

Slow-motion stage

Mercury-201

proton
neutron
alpha particle (2p + 2n)

Parent nucleus · 201 nucleons

80 protons (coral) and 121 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

20180Hg19778Pt+42He

Two protons and two neutrons leave together as one helium nucleus.

Z
8078
-2
A
201197
-4
n⁰
121119
-2

Energy released

5.20MeVtypical value
Alpha particle5.097 MeV
Mass convertedE = Δm c²0.00558 u
In joules8.33 × 10-13 J
Compared with a bonda C–C bond is 3.6 eV≈ 1,444,444 ×

Measured alpha energies fall between 4 and 9 MeV.

The particle

Charge
+2
Mass
4 u
Speed
About 5% of the speed of light
Ionising power
Very high
Stopped by
Stopped by a sheet of paper or dead skin