Other Modes of Radioactive Decay

Two other modes of radioactive decay are positron decay and electron capture. A positron is an electron with a positive charge and is symbolized +ie or p+. Positron decay is, in a sense, the opposite of beta decay—instead of a neutron turning into a proton, a proton turns into a neutron. The result is to decrease the atomic number by one unit, again without changing the mass number. This time, therefore, the daughter isotope is located one space to the left of the parent, instead of one space to the right. 

Positron decay is much less common than beta decay but also can occur throughout the periodic table. Here are several examples of positron decay  

Electron capture (EC) is also less common than beta decay, but it has the same net result as positron decay—the daughter isotope is located one space to the left of the parent. In electron capture, an orbiting electron is taken into the nucleus where it combines with a proton to form a neutron. An example of electron capture is the decay of silver-108, as 

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