Beta Decay Example

If you are looking for some beta decay examples that illustrates this radioactive decay type, this article will be helpful. In this article, I explain the process of beta decay and provide examples of the same.

During the last years of the nineteenth century, some physicists thought that all that had to be discovered in physics had already been discovered and all that remains is consolidation of facts. How wrong they were proved to be when in 1896, Becquerel discovered radioactivity! Radioactivity opened up a Pandora's box of problems related to the microcosm of the atomic nucleus. Subsequent development of the special theory of relativity and quantum physics opened up even bigger problems that would keep physicists busy for more than a century! One of the important findings of Becquerel was the discovery of the three types of radioactive decay, which are alpha decay, beta decay and gamma decay. This article has a clear explanation of the beta decay phenomenon. To better understand this radioactive decay process, I provide beta decay examples to illustrate the point.

What is Beta Decay?

Before I present the beta decay examples, let me explain the phenomenon. Radioactivity occurs due to the instability of atomic nucleus. It is the spontaneous emission of ionizing radiation by atoms of certain elements that have unstable nuclei. Beta decay involves the emission of an electron (e-) or a positron (e+, antiparticle of electron) from an atomic nucleus, causing its transformation into another element. As described there are two types of radioactive decay which involve beta decay (electron emission) and positron decay (positron emission).

Actually in both types of radioactive decay, a neutrino is also emitted along with the beta particles. Neutrinos are neutral particles with very little mass, that travel close to the speed of light. The energy of beta particles emitted varies according to how the energy is shared between them and the emitted neutrinos. That is why, the energy of emitted beta particles varies over a spectrum that extends up to a maximum energy value. Typical energies of beta particles are recorded to be from a few kilo electron volts to around 10 mega electron volts. High energy beta particles are spitted out of the nucleus at relativistic speeds!

In a beta decay reaction involving emission of an electron, an antineutrino is also emitted, while in positron decay, a neutrino is emitted. Prior to sharing beta decay examples with you, let me list the beta decay rules.

Beta Decay Rules

When studied at a deeper level, it was realized that beta decay was a result of proton and neutron decay at the nuclear level. A beta decay involving electron emission (also known as beta minus decay) occurs when a neutron inside the nucleus decays to a proton emitting an electron and an antineutrino. On the other hand, a positron emission (beta plus decay) is the result of a proton decaying into a neutron and it is accompanied by the emission of a neutrino.

Based on these facts, here are the governing beta decay rules, which you can verify through the beta decay examples provided below.

When an electron is emitted by a radioactive nucleus, the resulting transmuted nucleus has an atomic number greater than 1 (as it converts a neutron into a proton), while the atomic weight remains the same

When a positron is emitted, the resulting transmuted nucleus has its atomic number reduced by 1 (as it converts a proton into a neutron), while the atomic weight remains the same.

These rules need to be remembered when solving radioactive decay problems. Let us have a look at some real life beta decay examples and verify the above rules.

Examples of Beta Decay

Here are some beta decay examples that involve electron and positron emission.

137Cs55 -> 137Ba56 + e- + antineutrino

22Na11 -> 22Ne10 + e+ + neutrino

60Co27 -> 60Ni28 + e- + antineutrino

3H1 -> 3He2 + e- + antineutrino

14C6 -> 14N7 + e- + antineutrino

10C6 -> 10B5 + e+ + neutrino

If you have a look at the list of radioactive elements and their decay modes, you will realize that alpha decays are much more likely than beta decays. In some rare cases, a process called double beta decay may also occur, which involves the emission of two beta particles simultaneously.

Hope, these beta decay examples have clarified your understanding of this spontaneous radioactive decay phenomenon. In your physics lab course, you may conduct experiments using a Geiger counter to study beta decay in various radioactive elements.