GCSE PHYSICS - What is an Alpha Particle? - What are the Properties of an Alpha Particle? - Where do Alpha Particles come from?

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Alpha Particles.

What is an Alpha Particle?

An alpha particle (also written as α-particle) consists of
2 protons and 2 neutrons. An alpha particle
is the same thing as the nucleus of a helium atom.

What are the Properties of an Alpha Particle?

1. An alpha particle has a positive charge
because the 2 protons have a positive charge.

2. An alpha particle has by far the most mass of the
three types of radioactivity. It is the type most likely
to collide with other atoms which means that

(i) alpha particles have the least penetrating ability of the three types
and are easily absorbed by paper, skin or a few centimetres of air.

(ii) alpha particles are the most ionising of the three types.

Where do Alpha Particles come from?

Alpha particles are most likely to be emitted during the decay of
heavy nuclei which have a large number of protons and neutrons.
After an alpha particle has been emitted the atomic number and the
mass number changes and a new element is made (see examples).

How can the Direction of an Alpha Particle be Changed?

The positive charge on the alpha particle means that
it will be deflected by a magnetic field or an electric field
(like the charged droplets in an inkjet printer).
An alpha particle will be deflected less than a beta particle
because the alpha particle has a bigger mass.
An alpha particle has a positive charge and will be
deflected in the opposite direction
from a beta particle which has a negative charge.

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