What are the electric rays or particles emitted from an unstable nucleus during decay called?

The particles emitted from an unstable nucleus during radioactive decay are known as alpha particles. These particles consist of two protons and two neutrons, which essentially make them identical to helium nuclei. When a nucleus undergoes alpha decay, it emits an alpha particle as a way to reduce its mass and achieve a more stable state.

Alpha decay is one of the primary modes of radioactive decay, particularly for heavy elements. The emission of alpha particles often results in a significant change in the atomic number of the original nucleus, leading to the formation of a new element that is lower in the periodic table. This process is crucial for understanding the behavior of certain heavy isotopes and their transition to stability.

This foundational concept in nuclear physics highlights how unstable nuclei seek stability through various decay processes, making alpha particles a key focus in the study of radiation and its effects.