Atoms are small but can release lots of energy. When an
unstable atom changes into a more stable one, it gives off radioactivity. It
also gives off some of the potential energy locked inside the nucleus of the
atom. Some atoms can be made to produce a constant supply of nuclear energy in
a process called a chain reaction. Nuclear energy makes possible the
destructive power of nuclear bombs, but it also generates much of the
world’s electricity.
When a nuclear bomb detonates, it starts a runaway chain reaction
and releases enormous amounts of energy very quickly. A lump of radioactive
plutonium the size of a tennis ball can produce as much energy as tens of
thousands of tons of powerful explosives.
In nuclear fission (splitting), large atoms break into smaller
ones and give off energy. When a neutron is fired at the nucleus of a large
atom, the atom becomes unstable and splits into two smaller atoms. Energy is
produced and some neutrons are given off too. They collide with more large
unstable nuclei of the original material and continue the chain reaction.
In nuclear fusion (joining), massive energy is given off when
small atoms fuse together to make larger atoms. A neutron is released at the
same time. Stars like the Sun make their energy when nuclear fusion happens
inside them at extremely high temperatures and pressures. Scientists are hoping
that nuclear power stations will one day use fusion to provide Earth with a
clean and inexpensive source of energy.
BIOGRAPHY: LISE MEITNER Austro-Swedish, 1878-1968
Physicist Lise Meitner was one of the first to explain the process
of nuclear fission. She also predicted the idea of the nuclear chain reaction
before anyone had managed to make it work. She supported development of nuclear
power, but opposed the production of nuclear bombs.
