MCQ Detailed View

In nuclear chemistry, an alpha particle is the nucleus of a helium atom. It contains two protons and two neutrons and carries a positive charge of 2e. Alpha particles are commonly emitted during the radioactive decay of heavy elements like uranium, thorium, and radium.

Alpha particles are relatively large and heavy compared to beta and gamma radiation. Because of their size and charge, they have low penetration power and can be stopped by a sheet of paper or even a few centimeters of air. Despite this, they are highly ionizing, meaning they can easily knock electrons off atoms and molecules, which can cause chemical changes in nearby materials.

Other types of radiation are different. Beta particles are high-energy electrons with a negative charge, while gamma particles are high-energy electromagnetic radiation with no mass or charge. The option “negative particle” is incorrect because alpha particles are positively charged.

Understanding alpha particles is important in physical chemistry, nuclear physics, and radiation safety. Alpha decay reduces the mass and atomic number of a radioactive nucleus, transforming it into a different element. For example, when uranium-238 emits an alpha particle, it becomes thorium-234.

Alpha particles are also used in practical applications, such as in smoke detectors, nuclear energy, and medical treatments. Studying their properties helps students grasp radioactivity, particle emission, and energy release in nuclear reactions.

Thus, a helium nucleus consisting of two protons and two neutrons with a charge of 2e is called an alpha particle, a fundamental concept in nuclear chemistry and radiation studies.