Manganese (Mn) is a transition metal which possesses many oxidation states (charges). A compound made up of manganese and fluoride (F) exists in a simple cubic cell with the Mn atoms in the corners of the cell and the F anions in the center of each edge of the cell. Assume that F is a mono anion, the unit cell has no net charge and determine the charge of the Mn atom in this unit cell. Explain.