How do you work out the formula of an ionic compound?
an ionic compound is made when a metal reacts with a non-metal, to balance out the equation you must see what charges they are, eg copper, Cu and bromine Br react Cu has to loose 2 electrons making the it a position ion Cu2+ Br can only gain one electron for a full outer shell Br1+ we need to balance this out, the end formula will be CuBr2 since the charges are all cancelled out, use your periodic table to help you with finding out the charges