An isotope is an atom whose neutrons are not equal to its number of protons. Record the atomic mass from a specific element from the periodic table of elements.
Record the atomic number of that element from the periodic table of elements.
Subtract the atomic number from the atomic mass to get the number of neutrons in an atom.
If the number of neutrons is not equal to the atomic number, than the element exists naturally as an isotope. An isotope is an atom whose number of electrons do not equal the number of neutrons. An atom with more or less neutrons than protons is considered an isotope.
An ion is an atom that has gained or lost an electron. Atoms gain or lose electrons because of chemical bonding. Electrons are negatively charged. If you remove negativity in the form of electrons from an atom, an atom will become positive. If you increase negativity in the form of electrons in an atom, the atom will become negative. An atom becomes more negative or more positive depending on the quantity of electrons gained or lost.
Choose an atom from the periodic table of elements and record the number of protons, electrons and neutrons. Subtract an electron from the element. If you subtract one negatively charged electron, the atom will have a charge of positive 1, or +1. If you subtract two negatively charge electrons, the atom will have a charge of positive 2, or +2, and so on.
Choose an atom from the periodic table of elements and record the number of protons, electrons and neutrons. Add an electron to the atom. If you add one negatively charged electron, the atom will have a charge of negative 1, or -1. If you add two electrons, the atom will have a negative 2 charge, or -2, and so on.
To classify your atom, look at the final charge. If an atom has a positive charge it is considered a cation, and if it has a negative charge it is an anion.