What does alpha particle mean ?

Hint:Here, you are asked about alpha particles. In order to answer this question, you need to consider the source from which they occur and the process of how the alpha particles are generated. Also, you need to know that here what is going to be discussed is a part of nuclear physics.

Complete answer:
Alpha particle is a combination of two protons and two neutrons. These protons and neutrons are bound together closely to each other and make a single particle. This resulting particle is identical to the helium-4 nucleus. The alpha particles are generally produced in the process of alpha decay. The symbol for the alpha particle is the Greek letter alpha α or α+2. As they are identical to helium atoms, they are also represented as He+2. The +2 indicates that the helium atom is lacking two electrons. So, alpha particles are positively charged particles. The mass of an alpha particle is four units.

The most common known source of alpha particles is alpha decay. When an alpha particle is emitted by an atom in alpha decay, the mass number of the atom decreases by four because there is a loss of four nucleons in the alpha particle. As two protons are released in the process of alpha decay, the atomic number also decreases by two. As you can see that the composition of the original atom is changed, the atom is turned in to another new element.Alpha particles are released by large radioactive nuclei such as uranium, thorium and radium.

So, alpha particle is a positively charged particle which has two protons and two neutrons and is identical to helium.

Note: We have discussed in brief about the alpha particle. You should keep in mind that the alpha particle is a particle which has two protons and two neutrons held close together and are identical to helium atoms. Also keep in mind that the particle is a charged particle and its mass is four units. Note that alpha decay is not the only way to produce alpha particles there are other ways too but alpha decay is the most common process.