Download 6 - Electron Configurations - Chemistry

Electron Configurations
Quanta – a “packet” of energy
Locating Electrons: 4 Quantum Numbers
1) Principle Quantum Number
2) Sublevel
3) Orbital
4) Spin
(State)
(Town)
(Street)
(House #)
1) Principle – energy levels are a particular distance from the nucleus
# of electrons 
2
8
18
32
50
1
2
3
4
5
Nucleus 
Energy levels 
2) Sublevel – tells shape
--each energy level has a # of sublevels that is = to ‘n’
Energy level (n)
# of Sublevels
1
1
2
2
3
3
4
4
**there is no such thing as 1p, 2d, 3f
3)
4)
Orbital – each orbital can hold UP TO 2 electrons
Sublevel
Amount of Orbitals
s
1
p
3
d
5
f
7
Sublevels
1s
2s, 2p
3s, 3p, 3d
4s, 4p, 4d, 4f
Amount of electrons
2
6
10
14
Spin – indicates the direction of spin of an electron (either clockwise or counter clockwise)
--designated by an UP or DOWN arrow
Pauli Exclusion Principle:
-
No two electrons in an atom can have the same set of 4 quantum #’s
The 2 electrons in an orbital MUST have opposite spins
o Ex. Each electron has a different address
Electron Configuration Notation:
He has 2 e-s, so its electron configuration would be  1s2
Li has 3 e-s, so its electron configuration would be 
1s2 2s1
N has 7 e-s, so its electron configuration would be 
1s2 2s2 2p3
Ne has 10 e-s, so its electron configuration would be  1s2 2s2 2p6
Na has 11 e-s, so its electron configuration would be  1s2 2s2 2p6 3s1
OR
[Ne] 3s1
** Noble gases, elements in the last column on the periodic table, always end with a full ‘s’ and ‘p’
orbital so we can abbreviate the electron configurations up to those elements by putting the element in
brackets [ ] and then continuing from that point.
-
Degenerate orbital’s have the same energy.
o Ex. ALL 3p’s have the same energy.
1s
2s
2p
- to fill electrons we start with 1s and follow the arrows
3s
3p
3d
4s
4p
4d
4f
5s
5p
5d
5f
6s
6p
6d
7s
7p
from tail to head. The following is how electrons fill:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
Ex: Lead is Pb-82, it has 82 electrons so its configuration would look like:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p2
10e-s
20e-s
38e-s
56e-s
80e-s  end with a total of 82 electrons
OR we can abbreviate by using the noble gas Xenon [Xe] 6s2 4f14 5d10 6p2
** we can also use the periodic table to predict these configurations, please see me to find out how!