To keep track of valence electrons in an ionic compound, you can draw a Lewis dot structure. A Lewis dot structure is a diagram that shows the distribution of electrons in a molecule or ion. Each dot represents a valence electron. To draw a Lewis dot structure for an ionic compound, first write the chemical formula of the compound. Then, draw a dot for each valence electron of each atom. The dots are placed around the symbols of the atoms. For example, the Lewis dot structure for sodium chloride (NaCl) is:

Na Cl

. .

. .

The sodium atom has one valence electron, which is represented by the dot on the left side of the sodium symbol. The chlorine atom has seven valence electrons, which are represented by the seven dots on the right side of the chlorine symbol.

The total number of valence electrons in an ionic compound is equal to the sum of the valence electrons of all the atoms in the compound. In the case of sodium chloride, the total number of valence electrons is 8 (1 valence electron from sodium + 7 valence electrons from chlorine).

The Lewis dot structure can be used to determine the charge on an ion. The charge on an ion is determined by the difference between the number of valence electrons and the number of protons in the ion. For example, in the case of sodium chloride, the sodium ion has a charge of +1 because it has one valence electron and 11 protons. The chloride ion has a charge of -1 because it has seven valence electrons and 17 protons.