Each element in the periodic table has a different number of electrons moving around the nucleus. These electrons are organized into different layers and the outermost layer may contain from 1 to 8 electrons depending on which element it is.

An atom is most stable when there are 8 electrons in the outer layer but most elements do not have this.

An ionic bond between atoms forms when the electrons in the outer layers of two different atoms will add up to 8, so they can combine to make a "compound" with a full outer layer of electrons. The two different atoms are able to combine their electrons to become stable. When the bond is formed between the two atoms they are very close together and form a new material. For example:
Sodium is a metal with 1 electron in the outer layer and Chlorine has 7 electrons in the outer layer. These two atoms will go together to form an ionic bond because the 7 electrons from chlorine and +1 from sodium = 8!!

The ionic bond of these two atoms gives us Sodium Chloride.....or table salt. Also, when sodium gives off the one electron it gets positively charged and chlorine that takes up the electron gets negatively charged. Positively and negatively charged molecules are called ions (That is why it is called ionic bond).

The overall charge of the salt molecule, however, is neutral because we have as many positively charged particle as negatively charged ones.