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1
2
3
4
5
6
1
2
3
4
5
6
Ionization Energies
7
Be
900
Al
578
Si
787
Ti
659
V
651
Cr
653
Mn
717
Fe
762
Co
760
Ni
737
Cu
746
Zn
906
Ga
579
Ge
762
Nb
652
Mo
684
Tc
702
Ag
731
Cd
868
In
558
Sn
709
Sb
834
Ta
761
W
770
Re
760
Hg
1007
Tl
589
Pb
716
Bi
703
N
1402
O
1314
F
1681
Cl
1251
C
1086
S
1000
Br
1140
I
1008
Na
496
K
419
Rb
403
Cs
376
Ba
503
Fr
--
Ra
509
H
1312
B
801
P
1012
As
947
Se
941
Ru
710
Rh
720
Pd
804
Te
869
Os
839
Ir
878
Pt
868
Au
890
Po
812
At
--
Per
iod
Actinide series
Li
520
Ca
590
Sc
633
Sr
550
Y
600
Zr
640
Hf
659
Mg
738
La
538
Ac
490
Lanthanide series
Group 1
2
3 4 5 6 7 11 12
13 14 15 16 17
18
9
Ne
2081
Ar
1521
Kr
1351
Xe
1170
Rn
1038
He
2372
Rf
--
Db
--
Sg
--
Bh
--
Hs
--
Mt
--
Ce
534
Pr
527
Nd
533
Pm
536
Sm
545
Eu
547
Gd
592
Tb
566
Dy
573
Ho
581
Er
589
Tm
597
Yb
603
Lu
523
Th
587
Pa
570
U
598
Np
600
Pu
585
Am
578
Cm
581
Bk
601
Cf
608
Es
619
Fm
627
Md
635
No
642
Lr
--
Ds
--
Uub
--
Uut
--
Uuq
--
Uup
--
Uuu
--
Mg
738
Symbol
First Ionization Energy (kJ/mol)
8 10
First Ionization Energies(in kilojoules per mole)
H1312.1
Li520.3
Na495.9
K418.9
Be899.5
Mg737.8
Ca589.9
B800.7
Al577.6
Ga578.6
C1086.5
Si786.5
Ge761.2
N1402.4
P1011.8
As946.5
O1314.0
S999.7
Se940.7
F1681.1
Cl1251.2
Br1142.7
Ne2080.8
Ar1520.6
Kr1350.8
He2372.5
Rb402.9
Sr549.2
In558.2
Sn708.4
Sb833.8
Te869.0
I1008.7
Xe1170.3
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 188
First Ionization Energies(kJ/mol)
H1312.1
Li520.3
Na495.9
K418.9
Be899.5
Mg737.8
Ca589.9
B800.7
Al577.6
Ga578.6
C1086.5
Si786.5
Ge761.2
N1402.4
P1011.8
As946.5
O1314.0
S999.7
Se940.7
F1681.1
Cl1251.2
Br1142.7
Ne2080.8
Ar1520.6
Kr1350.8
He2372.5
Rb402.9
Sr549.2
In558.2
Sn708.4
Sb833.8
Te869.0
I1008.7
Xe1170.3
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 188
s p
First Ionization Energies(kJ/mol)
H1312.1
Li520.3
Na495.9
K418.9
Be899.5
Mg737.8
Ca589.9
B800.7
Al577.6
Ga578.6
C1086.5
Si786.5
Ge761.2
N1402.4
P1011.8
As946.5
O1314.0
S999.7
Se940.7
F1681.1
Cl1251.2
Br1142.7
Ne2080.8
Ar1520.6
Kr1350.8
He2372.5
Rb402.9
Sr549.2
In558.2
Sn708.4
Sb833.8
Te869.0
I1008.7
Xe1170.3
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 188
s p
MetalMetalloidNonmetal
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
n
HeH
1+ 2+
1e- 2e-
• Helium (He) has…
• a greater IE than H
• same shielding
• greater nuclear charge
Firs
t Ion
izat
ion
ener
gy
Atomic number
• Li has… • lower IE than H• more shielding
• Further away outweighs
greater nuclear charge H
He
Li
n
Firs
t Ion
izat
ion
ener
gy
Atomic number
Be has higher IE than Li same shielding
greater nuclear charge
H
He
Li
Be
n
BeLi
3+ 4+
2e- 2e-
1e- 2e-
1e-2e-3+ 2e-2e-4+
Firs
t Ion
izat
ion
ener
gy
Atomic number
B has lower IE than Be same shielding greater nuclear charge
p-orbitals available
H
He
Li
Be
B
n
BBe
4+ 5+
2e- 2e-
2e- 3e-
2s2p
1s
2e-2e-4+ 3e-2e-5+
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
2s2p
1s
n
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
n
2s2p
1s
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
n
2s2p
1s
• Breaks the pattern because removing an electron gets to 1/2 filled p orbital
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
n
2s2p
1s
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Nen
2s2p
1s
• Ne has a lower IE than He
• Both are full energy levels,
• Ne has more shielding
• Greater distance
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Ne
Na
n
2s2p
1s
3s
• Na has a lower IE than Li
• Both are s1
• Na has more shielding
• Greater distance
Firs
t Ion
izat
ion
ener
gy
Atomic number
Be has higher IE than Li same shielding
greater nuclear charge
H
He
Li
Be
n
BeLi
3+ 4+
2e- 2e-
1e- 2e-
Firs
t Ion
izat
ion
ener
gy
Atomic number
B has lower IE than Be same shielding greater nuclear charge
p-orbitals available
H
He
Li
Be
B
n
BBe
4+ 5+
2e- 2e-
2e- 3e-
2s2p
1s
Firs
t Ion
izat
ion
ener
gy
Atomic number
Na has a lower IE than Li
Both are s1
Na has more shielding Greater distanceH
He
Li
Be
B
C
N
O
F
Ne
Na
Firs
t Io
niza
tion
ener
gy
Atomic number
HeNe
Ar
Kr
H
Li
Na
K
Rb
Firs
t Io
niza
tion
ener
gy
Atomic number
HeNe
Ar
Kr
H
Li
Na
K
Rb
First Ionization Energy Plot
5 10 15 20 25 30 35 40
Atomic number
Fir
st i
on
izat
ion
en
erg
y (k
J/m
ol)
0
500
1000
1500
2000
2500
H
He
Li
Be
B
C
N
O
F
Ne
Mg
Na Al
Si
P
S
Cl
Ar
Ca
K
Sc
Ti
V
CrMn
FeCo Cu
Ni
Zn
Ga
Ge
As
Se
Br
Rb
Sr
Kr
B1+B
5+ 5+
2e- 2e-
3e- 2e-
3e-2e-5+ 2e-2e-5+ n
n
B2+B1+
5+ 5+
2e- 2e-
2e- 1e-
2e-2e-5+ 1e-2e-5+
n
B3+B2+
5+ 5+
2e- 2e-
2e- 0e-
1e-2e-5+ 0e-2e-5+
5+ Boron
B10.811
5
B3+ vs. He
0e-2e-2+0e-2e-5+
B2+ vs. Li
1e-2e-3+1e-2e-5+
B1+ vs. Be
2e-2e-4+2e-2e-5+
>
>
>
<
<
<
Isoelectronic
B = 1s22s22p1
B1+ = Be = 1s22s2
B2+ = Li =1s22s1
B3+ = He = 1s2
B1+B
3e-2e-5+ 2e-2e-5+ n
n
B2+B1+
2e-2e-5+ 1e-2e-5+
n
B3+B2+
1e-2e-5+ 0e-2e-5+
5+ Boron
B10.811
5
B3+ vs. He
0e-2e-2+0e-2e-5+
B2+ vs. Li
1e-2e-3+1e-2e-5+
B1+ vs. Be
2e-2e-4+2e-2e-5+
>
>
>
<
<
<
Isoelectronic
B = 1s22s22p1
B1+ = Be = 1s22s2
B2+ = Li =1s22s1
B3+ = He = 1s2
S1-S
S2-S1-
16+ Sulfur
S32.066
16
S2- vs. Ar
S1- vs. Cl<
<
>
>
IsoelectronicS = 1s22s22p63s23p4
S1- = Cl 1s22s22p63s23p5
S2- = Ar 1s22s22p63s23p6
16+ 2e- 8e- 6e- 16+ 2e- 8e- 7e- 16+ 2e- 8e- 7e- 17+ 2e- 8e- 7e-n
16+ 2e- 8e- 7e- 16+ 2e- 8e- 8e-
16+ 2e- 8e- 8e- 18+ 2e- 8e- 8e-n
Ionization Energies
• Energy is required to remove an electron from an atom to form a cation.
• Ionization energy () is the amount of energy needed to remove an electron from the gaseous atom E in its ground state:
E (g) + E+(g) + e-- energy required for reaction = .
• Ionization energy is always positive ( > 0).
• Larger values of mean that the electron is more tightly bound to the atom and is harder to remove.
• Units for ionization energies are kilojoules/mole (kJ/mol) or electron volts (eV) - 1 eV = 96.49 kJ/mol.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Ionization Energies (in kilojoules per mole)
Element
H
He
Li
Be
B
C
Al
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 190
1st
1312.1
2372.5
520.3
899.5
800.7
1086.5
577.6
2nd
5250.7
7298.5
1752.2
2427.2
2352.8
1816.7
3rd
11815.6
14849.5
3660.0
4620.7
2744.8
4th
21007.6
25027.0
6223.0
11577.5
5th
32828.3
37832.4
14831.0
6th
47279.4
18377.9
Ionization Energies (kJ/mol)
Element
H
He
Li
Be
B
C
Al
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 190
1st
1312.1
2372.5
520.3
899.5
800.7
1086.5
577.6
2nd
5250.7
7298.5
1752.2
2427.2
2352.8
1816.7
3rd
11815.6
14849.5
3660.0
4620.7
2744.8
4th
21007.6
25027.0
6223.0
11577.5
5th
32828.3
37832.4
14831.0
6th
47279.4
18377.9
Ionization Energies (kJ/mol)
Element
Na
Mg
Al
Si
P
S
Cl
ArHerron, Frank, Sarquis, Sarquis, Cchrader, Kulka, Chemistry 1996, Heath, page
1st
498
736
577
787
1063
1000
1255
1519
2nd
4560
1445
1815
1575
1890
2260
2295
2665
3rd
6910
7730
2740
3220
2905
3375
3850
3945
4th
9540
10,600
11,600
4350
4950
4565
5160
5770
5th
13,400
13,600
15,000
16,100
6270
6950
6560
7320
6th
16,600
18,000
18,310
19,800
21,200
8490
9360
8780Shaded area on table denotes core electrons.
Ionization Energies (kJ/mol)
Element
Na
Mg
Al
Si
P
S
Cl
ArHerron, Frank, Sarquis, Sarquis, Cchrader, Kulka, Chemistry 1996, Heath, page
1st
498
736
577
787
1063
1000
1255
1519
2nd
4560
1445
1815
1575
1890
2260
2295
2665
3rd
6910
7730
2740
3220
2905
3375
3850
3945
4th
9540
10,600
11,600
4350
4950
4565
5160
5770
5th
13,400
13,600
15,000
16,100
6270
6950
6560
7320
6th
16,600
18,000
18,310
19,800
21,200
8490
9360
8780Shaded area on table denotes core electrons.
ionization energy: the energy required to remove an e– from an atom
M + 1st I.E.
M + 2nd I.E.
M + 3rd I.E.
As we go , 1st I.E….
As we go , 1st I.E….
M1+ + e–
M2+ + e–
M3+ + e–
removes 1st e–
Each successive ionization requiresmore energy than the previous one.
decreases.
increases.
(due to the shielding effect)
Multiple Ionization Energies
Al Al+ Al2+ Al3+
578
kJ/m
ole
-
1817
kJ/
mol
e-
2745
kJ/
mol
e-
The second, third, and fourth ionization energies of aluminum are higher than the first because the inner electrons are more tightly held by the nucleus.
1st Ionizationenergy
2nd Ionizationenergy
3rd Ionizationenergy
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 190
Ionization Energies
• It takes more energy to remove the second electron from an atom than the first, and so on.
• There are two reasons for this trend: 1. The second electron is being removed from a positively
charged species rather than a neutral one, so more energy is required.
2. Removing the first electron reduces the repulsive forces among the remaining electrons, so the attraction of the
remaining electrons to the nucleus is stronger.
• Energy required to remove electrons from a filled core is prohibitively large and simply cannot be achieved in normal chemical reactions.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Factors Affecting Ionization Energy
Nuclear ChargeNuclear ChargeThe larger the nuclear charge, the greater the ionization energy.
Shielding effectShielding effectThe greater the shielding effect, the less the ionization energy.
RadiusRadiusThe greater the distance between the nucleus and the outer electrons of an atom, the less the ionization energy.
SublevelSublevelAn electron from a full or half-full sublevel requires additional energy to be removed.
Smoot, Price, Smith, Chemistry A Modern Course 1987, page 189
Formation of Cation
11p+
sodium atomNa
e-
loss of one valence
electron
e-
e-
e-
e-e-
e-
e-
e- e-
e-
sodium ionNa+
11p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
Formation of Anion
17p+
chlorine atomCl
e-
e-
e-
e-
e-e-
e-
e-
e- e-
e-
e-
e-
e-
e-
e-
e-
e-
gain of one valence
electron
chloride ionCl1-
17p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
Formation of Ionic Bond
chloride ionCl1-
17p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
sodium ionNa+
11p+e-
e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-