<Tr> <Th_colspan="2"> Structure </Th> </Tr> <Tr> <Td> Crystal structure </Td> <Td> Halite (cubic), cF8 </Td> </Tr> <Tr> <Td> Space group </Td> <Td> Fm3m, No. 225 </Td> </Tr> <Tr> <Td> Coordination geometry </Td> <Td> cubic </Td> </Tr>

Why is the chemical formula magnesium sulfide written as mgs and not mg2s2