<Tr> <Td> p </Td> <Td> </Td> <Td> 6 </Td> <Td> 2nd shell and higher </Td> <Td> principal </Td> </Tr> <Tr> <Td> d </Td> <Td> </Td> <Td> 10 </Td> <Td> 3rd shell and higher </Td> <Td> diffuse </Td> </Tr> <Tr> <Td> f </Td> <Td> </Td> <Td> 14 </Td> <Td> 4th shell and higher </Td> <Td> fundamental </Td> </Tr> <Tr> <Td> g </Td> <Td> </Td> <Td> 18 </Td> <Td> 5th shell and higher (theoretically) </Td> <Td> (next in alphabet after f, excluding j) </Td> </Tr>

Which element has a total of three shells with four electrons in the valence shell