We just learned a little about Mass.
A while back we learned about atoms,
and the parts inside of them protons, neutrons and electrons
Electrons have a negative charge, and Protons have a positive charge.
If an atom has more electrons than protons or more protons than electrons,
then we call it an ion.
If we know the number of electrons and protons, we can figure out whether it is more negative or more positive.
So if an atom has 4 electrons and 2 protons, then there are 2 more electrons.
This would give the atom a negative charge of 2.
An ion with a negative charge is called an anion.
If an atom has 6 protons and 2 electrons, then there are 4 more protons.
This would give the atom a positive charge of 4.
An ion with a positive charge is called a cation.
(from: wikipedia - ion)
