Electron Capture Nuclear Reaction Example

Worked Example Problem

Gamma ray universe
Gamma ray universe. Getty Images/JULIAN BAUM/SCIENCE PHOTO LIBRARY

This example problem demonstrates how to write a nuclear reaction process involving electron capture.


An atom of 13N7 undergoes electron capture and produces a gamma radiation photon.

Write a chemical equation showing this reaction.


Nuclear reactions need to have the sum of protons and neutrons the same on both sides of the equation. The number of protons must also be consistent on both sides of the reaction.

Electron capture decay occurs when a K- or L-shell electron is absorbed into the nucleus and converts a proton into a neutron. This means the ​number of neutrons, N, is increased by 1 and the number of protons, A, is decreased by 1 on the daughter atom. The energy level change of the electron produces a gamma photon.

13Na7 + + 0e-1ZXA + γ

A = number of protons = 7 - 1 = 6

X = the element with atomic number = 6

According to the periodic table, X = Carbon or C.

The mass number, A, remains unchanged because the loss of one proton is offset by the addition of a neutron.

Z = 13

Substitute these values into the reaction:

13N7 + e-13C6 + γ