Alpha particle

Alpha particles are tiny bits of matter. They are made of two protons and two neutrons stuck together. They look just like the nucleus of a helium-4 atom. We call them alpha particles because they are named after the first letter of the Greek alphabet, which is α.

These particles are made when some special materials change in a process called alpha decay. After they get two electrons, they become normal helium atoms.

Alpha particles can push other atoms apart, but they do not go very far. Usually, just a little bit of air or the top layer of your skin can stop them. Scientists have found some special alpha particles that can go farther, and some from cosmic rays can pass through many things.

The name “alpha particle” was given by a scientist named Ernest Rutherford. He studied radiation from uranium and found two kinds. He called one kind “α radiation.” Later, with help from Hans Geiger, they learned that alpha particles become helium atoms when they get electrons. This is how we get helium gas on our planet.