Question

What are the differences between alpha and beta particles?

Answer 1

To understand the difference between alpha particles and beta particles we first need to know about radioactive decay. Unstable atomic nuclei attain stability by losing energy and emitting energy in the form of EM waves or particles called radiation and this process is known as radioactive decay.

Complete answer:
There are various types of radiation and emitted particles that are produced when radioactive elements decay.
Two of these radiated particles are alpha ($\alpha$) particles and beta ($\beta$) particles.
Alpha ($\alpha$) particles
Alpha ($\alpha$) particles are a particle identical to the helium-4 nucleus ($_{2}^{4}He$) and are formed when two neutrons and two protons are bound together.
The alpha ($\alpha$) particles are most commonly formed during the process of alpha ($\alpha$) decay but can also be produced by other methods. For example
$_{88}^{226}Ra\xrightarrow{-\alpha }_{26}^{224}Rn+\alpha$
They are denoted by $\alpha$, ${{\alpha }^{2+}}$ or due to their similarities to the helium nucleus as $H{{e}^{2+}}$ or $_{2}^{4}H{{e}^{2+}}$.
Since alpha ($\alpha$) particles are produced during the radioactive decay mechanism, they usually have a kinetic energy of 5MeV and have a speed in the range of 4% of the speed of light.
The net spin of alpha ($\alpha$) particles is 0.
They have low penetration depth and can be stopped by skin or a few cms of air.
Also due to particle radiation, they are highly ionizing.
Beta ($\beta$) particles
A positron or an electron is emitted during the beta ($\beta$) decay of an atomic nucleus and has a high speed and high energy. These emitted particles are known as beta ($\beta$) particles.
When electrons are produced, the beta decay forms ${{\beta }^{-}}$ , and when positrons are produced, the beta decay forms ${{\beta }^{+}}$. For example,
$_{6}^{14}C\to _{7}^{14}N+{{\beta }^{-}}$
$_{8}^{15}O\to _{7}^{15}N+{{\beta }^{+}}$
The beta ($\beta$) particles have energy dependent on the distance, and at a range of about 1 m in the air, it has an energy of 0.5 MeV.
The beta ($\beta$) particles are less ionizing than alpha ($\alpha$) particles.
Since with the increase in ionizing power of a particle, its penetrating power decreases, so we can conclude that beta ($\beta$) particles have higher penetrating power than alpha ($\alpha$) particles.

Note:
It should be noted that another type of particle is emitted during radioactive decay of the atomic nucleus known as gamma ($\gamma$) particles. They are short wave EM radiation having no charge or mass and are emitted when the nucleus is left in an excited state after $\alpha$-decay or $\beta$-decay. Hence their emission will only result in a decrease in the energy of the nucleus.