# What is the equation for electron capture of uranium 237?

May 11, 2014

The equation is

""_92^237"U" + _-1^0"e" →_91^237"Pa" + ν_e

In electron capture, the nucleus pulls an outside electron into the nucleus. The electron combines with a proton to make a neutron and emits an electron neutrino.

Some texts omit the neutrino in the equation because it has no mass or charge. It serves only to carry away the excess energy.

""_-1^1"H" + _-1^0"e" → _0^1"n" + ν_e

Since proton becomes a neutron, the number of protons decreases by 1, but the atomic mass stays the same.

One example of electron capture involves uranium-237.

""_92^237"U" + _-1^0"e" →_91^237"Pa" + ν_e