Question

How does alpha decay affect the nucleus?

Answer 1

In alpha decay the nucleus loses 2 protons and 2 neutrons.

Explanation:

An alpha (`alpha`) particle is similar to the nucleus of a helium atom i.e. 2 protons and 2 neutrons. The atomic mass of the nucleus that emits an `alpha`-particle will decrease by four and the atomic number decreases by two. In general terms:

In which `X` is a nuclide that exhibits alpha decay and `Y` the resulting nuclide. Due to `alpha`-decay:

• `A`, the atomic mass (protons + neutrons), decreases by four, because the emitted `alpha`-particle contains 2 protons and 2 neutrons.
• `Z`, the atomic number (number of protons), decreases by two, because the emitted `alpha`-particle contains 2 protons.

An example of this process is the decay of radium-226 to radon-222:

Note that sometime `""_2^4 alpha` is given as `""_2^4He` which is essentially the same.