# How does alpha decay affect the nucleus?

Jun 16, 2016

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.