The atomic structure is such that the protons and neutrons are housed within the central nucleus of an atom. The electrons are located in either an orbit or cloud that surrounds this dense, central nuclear core. The atomic number above the symbol of each element on the periodic table represent the number of protons found in the core of an atom of that element. In a neutral atom, the number of positive protons equals the number of negatively charged electrons. (If you have an equal number of positives as you do negative, then the sum is zero, or neutral).
Ions are charged atoms. The charge is due to the fact that the number of electrons is different than the number of protons within that atom. If there are more electrons than there are protons, then the ion will be negatively charged. A negatively charged ion is called anion. If there are less electrons than there are protons, then the ion will be positively charged. A positively charged ion is called a cation.