Atoms are the basic units of matter and the defining structure of elements. The term "atom" comes from the Greek word for indivisible, because it was once thought that atoms were the smallest things in the universe and could not be divided. We now know that atoms are made up of three particles: protons, neutrons and electrons — which are composed of even smaller particles, such as quarks.
Anion vs. Cation
Ions result from atoms or molecules that have gained or lost one or more valence electrons, giving them a positive or negative charge. Those with a negative charge are called anions and those with a positive charge are called cations. These opposing charges frequently result in ionic bonds with one another.
An anion is an ion that carries a negative charge, causing it to migrate to the anode (positive electrode) in electrolysis. It has more electrons than protons, resulting in the negative charge. Anions are nonmetals.
A cation is an ion that carries a positive charge, causing it to migrate to the cathode (negative electrode) in a electrolysis. It has more protons than electrons, resulting in the positive charge. Cations are metals.