3.04 Atomic Structure and Electronic Configuration
Arranging the electrons in an atom
Learning Objectives/TerminologyAufbau
Pauli Exclusion Principle
Ne-Va-S-P
Dr. F. O. Garces
Chemistry 100
Miramar College
1
3.05 Atomic Structure and Electronic Configuration
January 10
Electronic Configuration
How are the electrons of an atom arranged in the atom?
What are shells and orbitals arrange outside the nuclei of an atom?
How is the e- arrangement liken to that of a Hotel room (Hotel del Orbital) ?
What is the importance of the valence electrons and how do these influence chemistry?
2
3.05 Atomic Structure and Electronic Configuration
January 10
PreLude to eConfiguration
Placing electrons in orbitals to complete the electron configuration.
3
3.05 Atomic Structure and Electronic Configuration
January 10
Shells and Orbitals
4
3.05 Atomic Structure and Electronic Configuration
January 10
Relative Energies for Shells and Orbitals
s
p
d
f
∞
8
7
6
5
4
3
2
1
5
3.05 Atomic Structure and Electronic Configuration
Relative
Energies
of the
orbitals
January 10
The First 10 elements:
1s
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
6
H = 1s1
He = 1s2
Li = 1s2 2s1
Be = 1s2 2s2
B = 1s2 2s2 2p1
C = 1s2 2s2 2p2
N = 1s2 2s2 2p3
O = 1s2 2s2 2p4
F = 1s2 2s2 2p5
Ne = 1s2 2s2 2p6
+
+
2s
2p
3.05 Atomic Structure and Electronic Configuration
January 10
Electron Configuration
Hydrogen and Helium
H
H = 1s1
1s
2s
2p
1s
2s
2p
He
He = 1s2
Pauli Exclusion Principle
7
3.05 Atomic Structure and Electronic Configuration
January 10
Relative Energies for Shells and Orbitals
s
p
d
f
∞
8
7
6
5
4
3
2
1
8
3.05 Atomic Structure and Electronic Configuration
Relative
Energies
of the
orbitals
January 10
Electron Configuration:
Lithium to Beryllium
+
Li
+
=
1s
2s
2p
1s
2s
2p
Li = 1s2 2s1
+
Be
+
=
Be = 1s2 2s2
Aufbau Process
9
3.05 Atomic Structure and Electronic Configuration
January 10
Relative Energies for Shells and Orbitals
s
p
d
f
∞
8
7
6
5
4
3
2
1
10
3.05 Atomic Structure and Electronic Configuration
Relative
Energies
of the
orbitals
January 10
Electron Configuration:
+
+
B
Boron to Nitrogen
=
1s
2s
2p
1s
2s
2p
B = 1s2 2s2 2p1
+
C
+
=
Hund’s Rule
C = 1s2 2s2 2p2
+
N
+
=
1s
2s
2p
Paramagnetic
N = 1s2 2s2 2p3
11
3.05 Atomic Structure and Electronic Configuration
January 10
Relative Energies for Shells and Orbitals
s
p
d
f
∞
8
7
6
5
4
3
2
1
12
3.05 Atomic Structure and Electronic Configuration
Relative
Energies
of the
orbitals
January 10
Electron Config:
Oxygen to Neon
+
O
+
=
1s
2s
2p
1s
2s
2p
O = 1s2 2s2 2p4
+
F
+
=
F = 1s2 2s2 2p5
+
Ne
+
=
1s
2s
2p
Diamagnetic
Ne = 1s2 2s2 2p6
13
3.05 Atomic Structure and Electronic Configuration
January 10
Relative Energies for Shells and Orbitals
s
p
d
f
∞
8
7
6
5
4
3
2
1
14
3.05 Atomic Structure and Electronic Configuration
Relative
Energies
of the
orbitals
January 10
Electron Configuration using the Periodic Table
When using the Periodic table to determine the electron
configuration of an atom, it is important to understand the
layout of the periodic table.
The row of a periodic table can be used to determine which
energy level, 1, 2, 3... the valence electrons are located. The
column of the periodic table helps determine how many valence
electron an atom possesses. Elements in the 1A column (family)
have one valence electron, in the IIA column, elements have two
valence electron, in the IIIA family, elements have three
valence electrons, and so on.
15
3.05 Atomic Structure and Electronic Configuration
January 10
Electron Configuration using the Periodic Table
The elements designated in
-block is where the very last electrons are found in the s-orbitals.
Therefore the elements in portion of the periodic table is referred to as the s-block elements.
The elements designated in
-block is where the very last electrons are found in the p-orbitals.
The elements found in this portion of the periodic table is referred to as the p-block elements.
The same can be said about the
-block and -block with the elements found in this portion of the
periodic table referred to as the d-block (transition metals) and f-block (man-made) elements.
16
3.05 Atomic Structure and Electronic Configuration
January 10
Electron Configuration: ne-va-s-p
•  ne - number of electrons; the total number of electrons
•  va - valence electrons; the number of valence electrons
•  s - shell of valence electrons
•  p - previous noble gas
1
IA
H
1s1
2
Li Be
2s1 2s2
3
4
Na Mg IIIB
IVB
3s1 3s2
K
Ca Sc Ti
1
4s 4s2 3d1 3d2
Rb Sr
Y Zr
2
1
5s 5s 4d1 4d2
Cs Ba La Hf
6s1 6s2 5d1 5d2
Fr Ra Ac Db
7s1 7s2 6d1 6d2
3
4
5
6
7
17
2
IIA
1
5
VB
6
VIB
7
VIIB
V
Cr Mn
3d3 4s13d5 3d5
Nb Mo Tc
4d3 5s14d5 4d5
Ta W Re
5d3 6s15d5 5d5
Jl Rf Bh
6d3 7s16d5 6d5
8
9
VIIIB
Fe Co
3d6 3d7
Ru Rh
4d6 4d7
Os
5d6
Ir
5d7
Hn Mt
6d6 6d7
10
11
IB
12
IIB
Ni Cu Zn
3d8 4s13d10 3d10
Ni Ag Cd
4d8 5s14d10 4d10
Ni Au Hg
5d8 6s15d10 5d10
13
IIIA
14
IVA
B
2p1
F
C
N O
2p2 2p3 2p4 2p5
Cl Ar
P S
Si
3p2 3p3 3p4 3p5 3p6
Ge As Se Be Kr
4p2 4p3 4p4 4p5 4p6
I
Xe
Sn Sb Te
5
2
5p 5p3 5p4 5p 5p6
Pb Bi Po At Rn
6p2 6p3 6p4 6p5 6p6
Al
3p1
Ga
4p1
In
5p1
Tl
6p1
15
VA
16
VIA
17
VIIA
18
VIIIA
He
1s2
Ne
2p6
e- config. for Sulfur ?
3.05 Atomic Structure and Electronic Configuration
January 10
Electron Configuration: Sulfur
s
1
IA
- shell of
valence
electrons
= 3
•  ne - number of electrons; the total number of electrons
•  va - valence electrons; the number of valence electrons
•  s - shell of valence electrons
•  p - previous noble gas
18
VIIIA
2
IIA
13
IIIA
Li
2s1
Be
2s2
3
Na
3s1
Mg
3s2
3
IIIB
4
IVB
4
K
4s1
Ca
4s2
Sc
3d1
V
Ti
Cr Mn
3d2 3d3 4s13d5 3d5
5
Rb
5s1
Sr
5s2
Y
4d1
6
Cs
6s1
Ba
6s2
7
Fr
7s1
Ra
7s2
1
H
1s1
2
5
VB
6
VIB
7
VIIB
8
10
11
IB
12
IIB
15
VA
16
VIA
17
VIIA
He
1s2
B
2p1
C
N
O
2p2 2p3 2p4
F
2p5
Ne
2p6
Al
3p1
Si
3p2
P
S
S
3p3 3p4
Cl
3p5
Ar
3p6
Ni
3d8
Cu
4s13d10
Zn
Ga
3d10 4p1
Ge
4p2
As
4p3
Se
4p4
Be
4p5
Kr
4p6
Nb Mo Tc Ru
Zr
4d2 4d3 5s14d5 4d5 4d6
Rh Ni
4d7 4d8
Ag
5s14d10
Cd
In
4d10 5p1
Sn
5p2
Sb
5p3
Te
5p4
I
5p5
Xe
5p6
La
5d1
Hf Ta
W Re Os
5d2 5d3 6s15d5 5d5 5d6
Ir
Ni
5d7 5d8
Au
6s15d10
Hg
Tl
5d10 6p1
Pb
6p2
Bi
Po At
6p3 6p4 6p5
Rn
6p6
Ac
6d1
Db
6d2
Bh
Jl
Rf
6d3 7s16d5 6d5
Fe Co
3d6 3d7
p - previous
noble gas
= Ne (10 e-)
Hn Mt
6d6 6d7
e- config for Sulfur
S = [Ne]3s23p4
18
9
VIIIB
14
IVA
Va - valence electrons;
the number of
valence electrons
=6
ne - number of electrons; the total
number of electrons; this equals the
number of protons or atomic number
= 16
3.05 Atomic Structure and Electronic Configuration
January 10
Electron arrangement for the Sulfur atom
The 16 electrons for sulfur
occupy the shells & orbitals
of sulfur from the lowest
energy to the highest.
∞
s
p
d
f
8
7
6
5
4
e- config for Sulfur
S = [Ne] 3s2 3p4
3
16 total electrons
2
S
Relative
Energies
of the
orbitals
and the
filling
order.
1
19
3.05 Atomic Structure and Electronic Configuration
January 10
Electron arrangement for the Scandium atom
The 16 electrons for sulfur
occupy the shells & orbitals
of sulfur from the lowest
energy to the highest.
e- config for Scandium
Sc = [Ar]4s23d1
∞
s
p
d
f
8
7
6
5
4
3
21 total electrons
2
Sc
Relative
Energies
of the
orbitals
and the
filling
order.
1
20
3.05 Atomic Structure and Electronic Configuration
January 10
Electron arrangement for the Scandium atom
The 16 electrons for sulfur
occupy the shells & orbitals
of sulfur from the lowest
energy to the highest.
e- config for Tin
Sn = [Kr]5s24d105p2
∞
s
p
d
f
8
7
6
5
4
3
50 total electrons
2
Sn
Relative
Energies
of the
orbitals
and the
filling
order.
1
21
3.05 Atomic Structure and Electronic Configuration
January 10
The First 20 elements:
1s
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
22
H = 1s1
He = 1s2
Li = 1s2 2s1
Be = 1s2 2s2
B = 1s2 2s2 2p1
C = 1s2 2s2 2p2
N = 1s2 2s2 2p3
O = 1s2 2s2 2p4
F = 1s2 2s2 2p5
Ne = 1s2 2s22p6
Na = 1s2 2s22p63s1 Mg = 1s2 2s22p63s2 Al = 1s2 2s22p63s23p1
Si = 1s2 2s22p63s23p2
P = 1s2 2s22p63 s23p1
S = 1s2 2s2 2p63s23p4
Cl = 1s2 2s2 2p63s2 3p5
Ar = 1s2 2s2 2p6 3s2 3p6
+
+
2s
2p
+
+
3s
3p
3.05 Atomic Structure and Electronic Configuration
January 10
Assignment:
Determine the electron configuration.
1. Write out the electron configurations for the following atoms and ions.
Determine the number of unpaired electrons in the ground state.
+2
-3
-1
+2
13Al
12Mg
50Sn
15P
34Se
32Ge
2. Write the electron box diagram for the following elements.
Which have identical electron configuration (isoelectronic) ?
S-2
Cl
Ar
Ca+2
3. What does the term: Aufbau, Pauli Exclusion and Hund’s Rule mean?
4. How does atomic radius change as one goes left to right along the periodic table?
Explain*.
5. How does the ionization change as one goes down the periodic table? Explain*.
* Explain, means explain why.
23
3.05 Atomic Structure and Electronic Configuration
January 10