What does ionization mean?

Answer 1

Alpha particles have a big mass and a charge of +2. The positive charge means they cause lots of ionization in a short distance.

Each time the alpha particle rips an electron off a molecule it loses some energy and slows down a bit. An alpha particle might make 100 000 ionizations before it loses all its energy. It grabs two electrons and becomes a helium atom.

An alpha particle will ionize most air molecules it passes close to, which is why it loses energy so quickly and has a short range in air. This is why the cloud trails are short and fat.

The alpha particle has quite a big mass. So it's difficult to change its direction. This makes the path straight.

Answer 2

Ionization is the physical process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions.