# What is K-electron capture?

Sep 17, 2015

K-electron capture is the capture of a $1 s$ electron by the nucleus of an unstable isotope.

#### Explanation:

Electron capture occurs when the nucleus of an unstable isotope captures an inner-orbital electron.

In the process, a proton combines with the electron and forms a neutron, and an X-ray is released in the process.

The atomic number decreases by one unit, but the mass number remains unchanged.

The captured electron usually comes from the $1 s$ or $2 s$ orbitals, because these are closest to the nucleus.

If the electron comes from the $1 s$ level (the K-shell), the process is called K-electron capture.

Capture from the $n = 2$ level is called L-electron capture, and so on.