Question

An alpha-particle has how many neutrons?

Answer 1

Let us first understand about particles. A particle is a small, localised entity to which physical or chemical properties such as shape, density, and mass can be assigned. Based on their mass, particles may also be used to construct scientific models of much larger structures.

Complete answer:
Let us get some ideas about alpha-particle. Alpha particles, also known as alpha rays or alpha radiation, are made up of two protons and two neutrons bound together to form a helium-$4$ nucleus-like particle. They're usually made during the alpha decay process, but they can also be made in other ways.

Alpha particles are named after the Greek alphabet first letter $\alpha$. The alpha particle is represented by the symbol $\alpha$ or ${\alpha ^{2 + }}$. They are also written as $H{e^{2 + }}$or $_2^4H{e^{2 + }}$ meaning a helium ion with $a + 2$ charge, since they are similar to helium nuclei (missing its two electrons). The alpha particle becomes a natural (electrically neutral) helium atom $_2^4He$ after gaining electrons from its surroundings.

The net spin of alpha particles is zero. Alpha particles have a kinetic energy of about $5$ MeV and a velocity of about $4\%$ of the speed of light due to the process of their formation in normal alpha radioactive decay. They are a form of particle radiation that is highly ionising and has a shallow penetration depth.

Note: With two protons and two neutrons, an alpha particle is a very stable particle configuration. The ratio of protons to neutrons in the parent nucleus is reduced by alpha radiation, resulting in a more stable structure.