<Tr> <Td> 7 </Td> <Td> Nitrogen </Td> <Td> 2, 5 </Td> <Td> 15 </Td> </Tr> <Tr> <Td> 8 </Td> <Td> Oxygen </Td> <Td> 2, 6 </Td> <Td> 16 </Td> </Tr> <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>

How many electrons can fit in each principal energy level