Page 9 - Curriculum Visions Dynamic Book

 In 1917, scientist Ernest Rutherford was the first person to change one element into another. He transformed nitrogen into oxygen. In this picture, Lord Rutherford (centre) is accompanied by Dr E. S. Walton (left) and
Dr J. D. Cockroft (right).
 Different forms of radiation have different powers of penetration.
Alpha particles are the least penetrating, and reach only a few centimetres from the radioactive source. This is why plutonium and uranium can be handled safely with rubber gloves. Beta particles will travel a few metres
and penetrate bodies, but are stopped by metals. Gamma rays (emitted by,
for example, cobalt-60) will travel for several kilometres from the radioactive source and they will penetrate through most metals. They are only stopped by lead and thick concrete. Neutrons can be absorbed by dense polythene, water, concrete (which contains water) and other compounds that contain hydrogen.
alpha particle: a stable combination of two protons and two neutrons, which is ejected from the nucleus of a radioactive atom as it decays. An alpha particle is also the nucleus
of the atom of helium. If it captures two electrons it can become a neutral helium atom.
beta particle: a form of radiation in which electrons are emitted from an atom as the nucleus breaks down.
electron: a tiny, negatively charged particle that is part of an atom. The flow of electrons through a solid material such as a wire produces an electric current.
gamma rays: waves of radiation produced as the nucleus of a radioactive element rearranges itself into a tighter cluster of protons and neutrons. Gamma rays carry enough energy to damage living cells.
nucleus: the core of an atom, a tiny region where protons and neutrons are held together.
neutron: a particle inside the nucleus of an atom that is neutral and has no charge.
proton: a positively charged particle in the nucleus of an atom that balances out the charge of the surrounding electrons.
radioactive decay: a change in a radioactive element due to loss of mass through radiation. For example uranium decays (changes) to lead.
Aluminium Hand (1 mm thick)
Lead
(1.5 mm thick)
Concrete
Alpha radiation
Beta radiation
Gamma radiation
Neutron radiation
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