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Electron Location
Part II
Quantum Numbers
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Principal quantum number (n) - describes the
SIZE of the orbital or ENERGY LEVEL of the
atom.
Angular quantum number (l) or sublevels describes the SHAPE of the orbital.
Magnetic quantum number (m) - describes an
orbital's ORIENTATION in space.
Spin quantum number (s) - describes the SPIN
or direction (clockwise or counter-clockwise) in
which an electron spins.
Principle Quantum Number (n) or
Energy Level
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integer values used to specify the shell/size/level
the electron is in
describes how far away from the nucleus the
electron shell or level under consideration is
the lower the number, the closer the energy level
is to the atom's nucleus and less energy
maximum # of electrons that can fit in an energy
level is given by formula 2n2
Angular Quantum Number (l)
or Sub-level
determines the shape of the orbital
 they are numbered but are also given
letters referring to the orbital type

 l=0
refers to the s-orbitals
 l=1
refers to the p-orbitals
 l=2
refers to the d-orbitals
 l=3
refers to the f-orbitals
Magnetic quantum number (m)
or Orbitals
the third of a set of quantum numbers
 tells us how many orbitals there are of a
particular type and their orientation in
space of a particular orbital
 only two electrons can fit in an orbital

= electron

S – orbitals
only holds two electrons
P – orbitals
holds up to six electrons
P - orbitals
http://www.ul.ie/~walshem/fyp/porbital.gif
D – orbitals
holds up to 10 electrons
F – orbitals
holds up to 14 electrons
http://www.shsu.edu/~chm_tgc/BbAIF/PDB
s/applet/PDBorbitals.html
Spin quantum number (s)
the fourth of a set of quantum numbers
 number specifying the direction of the spin
of an electron around its own axis.

 only
two electrons of opposite spin may
occupy an orbit
 the only possible values of a spin quantum
number are +1/2 or -1/2.
Principle
Quantum # (n)
LEVEL/SIZE
Angular
Quantum # (l)
ORBITAL
SHAPE or
SUBLEVEL
Magnetic
Quantum #
(m)
AXIS/
ORIENTATION
or ORBITALS
1
2
s
s p
s
p
d
s
p
d
f
1
1
1
3
5
1
3
5
7
3
3
4
1
orbital
4 total
orbitals
9 total orbitals
2 e-
8 e-
18 e-
16 total orbitals
Spin
Quantum # (s)
DIRECTION
OF
ELECTRON
SPIN
32 e-
Table 3-6b Orbitals and Electron Capacity of the First Four Principle Energy
Levels
Principle
energy
level (n)
1
2
3
4
Number of
orbitals
per type
Number of
orbitals
per
level(n2)
s
1
1
2
s
1
p
3
4
8
s
1
p
3
9
18
d
5
s
1
p
3
d
5
16
32
f
7
Type of
sublevel
Maximum
number of
electrons
(2n2)