<Tr> <Th> n = 5 </Th> <Td> 0 </Td> <Td> − 1, 0, 1 </Td> <Td> − 2, − 1, 0, 1, 2 </Td> <Td> − 3, − 2, − 1, 0, 1, 2, 3 </Td> <Td> − 4, − 3, − 2, − 1, 0, 1, 2, 3, 4 </Td> <Td> </Td> </Tr> <Tr> <Th>... </Th> <Td>... </Td> <Td>... </Td> <Td>... </Td> <Td>... </Td> <Td>... </Td> <Td>... </Td> </Tr> <P> Subshells are usually identified by their n (\ displaystyle n) - and l (\ displaystyle \ ell) - values . n (\ displaystyle n) is represented by its numerical value, but l (\ displaystyle \ ell) is represented by a letter as follows: 0 is represented by' s', 1 by' p', 2 by' d', 3 by' f', and 4 by' g' . For instance, one may speak of the subshell with n = 2 (\ displaystyle n = 2) and l = 0 (\ displaystyle \ ell = 0) as a' 2s subshell' . </P> <P> Each electron also has a spin quantum number, s, which describes the spin of each electron (spin up or spin down). The number s can be + 1 / 2 or − 1 / 2 . </P>

Who came up with the electron cloud model