<Tr> <Td> 9 </Td> <Td> Fluorine </Td> <Td> 2, 7 </Td> <Td> 17 </Td> </Tr> <Tr> <Td> 10 </Td> <Td> Neon </Td> <Td> 2, 8 </Td> <Td> 18 </Td> </Tr> <Tr> <Td> 11 </Td> <Td> Sodium </Td> <Td> 2, 8, 1 </Td> <Td> </Td> </Tr> <Tr> <Td> 12 </Td> <Td> Magnesium </Td> <Td> 2, 8, 2 </Td> <Td> </Td> </Tr>

How many electrons in a full outer shell