Diagram of a nitrogen atom Inside a red giant star, the star
smashes lighter atoms together and gets energy to burn, and also
has heavier atoms left over. Nitrogen is one of these heavier
atoms, left over when a star smashes together carbon atoms.
Nitrogen is not very heavy, though, and a lot of stars make a
lot of nitrogen. When the red giant star explodes into a
supernova, the nitrogen inside it goes shooting off into space,
where it becomes part of a nebula, or cloud of space dust. All
of the nitrogen in the universe comes from inside stars. Most of
the nitrogen in the universe stays in these nebulae, usually
joining up with other nitrogen atoms to make molecules of two
nitrogen atoms. Nitrogen atoms have five electrons in their
outer ring, but they have room for eight electrons there. Often
they join up with another nitrogen atom, each sharing electrons
to fill up the rings. Because these nitrogen molecules are very
stable, they don't break apart and join up with other kinds of
atoms very much. It takes a