Download Simplified Nuclear Fusion

Simplified Nuclear Fusion
In nuclear fusion reactions light atoms such as hydrogen fuse into heavier elements. In nuclear
fission reactions heavy atoms such as uranium split.
Nuclear reactions change the nuclei of atoms so that atoms change from one element into
another. The two basic types of nuclear reactions are nuclear fusion and nuclear fission
reactions.
Sometimes people have trouble remembering which is fusion and which is fission. Remember
that the word fuse means join together, so fusion reactions are lighter atoms joining together
into heavier atoms. A fissure is a split, so fission reactions involve splitting heavy atoms into
lighter elements.
Nuclear Fusion
The simplest nuclear fusion reaction is hydrogen to helium. Four hydrogen atoms fuse to make
one helium atom and some byproducts, including energy. Like most nuclear reactions, the
reaction does not occur in one step. In several steps, four hydrogen atoms fuse into helium.
This reaction releases energy because the helium atom produced has very slightly less mass
than the four hydrogen atoms that started the reaction. In all energy producing nuclear reactions,
the total mass of the products after the reaction is less than the total mass before the reaction.
The lost mass is converted into energy.
Hydrogen into helium is the most common nuclear fusion reaction. These reactions provide the
energy for our Sun and other stars. When the hydrogen runs out, elements as heavy as iron are
also made by nuclear fusion reactions in massive stars.
Fusing atoms of elements heavier than iron requires energy rather than releases energy. So
fusion reactions making atoms heavier than iron only occur only when there is a huge
abundance of energy, such as when a massive star explodes as a supernova.