The shape of the orbital is determined by a quantum number which is represented by a symbol:
designates the overall shape of the orbital within a shell
affects orbital energies (larger = higher energy)
all electrons in an atom with the same value of are said to belong to the same sublevels
only integer values between 0 and n-1 are allowed
sometimes called the orbital angular momentum quantum number
spectroscopists use the following notation for sublevels
determines the orientation of orbitals within a sublevel.
does not affect orbital energy (except in magnetic fields!)
only integer values between -l and +l are allowed
the number of m values within a sublevel is the number of orbitals within a sublevel
several experimental observations can be explained by treating the electron as though it were spinning
spin makes the electron behave like a tiny magnet
spin can be clockwise or counterclockwise
the spin quantum number can have values of +1/2 or -1/2 (arrow up or arrow down)