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Chemistry
Unit 4: The Periodic Table
and Periodicity
The Origin of Elements
Element names come from a variety of sources
elements known to the ancients…S, Sn, C, Cu, Au
place names… Fr, Po, Ge, Ga, Eu, Am, Cf, Sc
famous people… Es, Fm, Md, No, Lr, Rf, Bh, Ro?
foreign languages… W, Fe, Au, Ag, Pb, Sn, Ni
mythology-related names… Th, Pm, Ta, Ti, Pd
names related to element properties… Rb, Sb, Ir
Background on the Periodic Table
Dmitri Mendeleev: given credit
for Periodic Table (~1870)
-- organized Table by
increasing atomic mass
-- left spaces and predicted
properties of undiscovered
elements
Mendeleev
Henry Moseley: put elements in
order of increasing
atomic number
____________.
Moseley
Mendeleev’s Early Periodic Table
REIHEN
TABELLE II
GRUPPE I
___
Li = 7
K = 39
11
12
RH3
R2O5
Cs = 133
Sr = 87
GRUPPE VI
GRUPPE VII
RH2
RO3
In = 113
? Di = 138
__
__
(Au = 199)
__
? Yt = 88
Ba = 137
__
Si = 28
RH
R2O7
? Er = 178
Tl= 204
__
V = 51
Zr = 90
GRUPPE VIII
___
RO4
Cr = 52
Nb = 94
? Ce = 140
From Annalen der Chemie und Pharmacie, VIII, Supplementary Volume for 1872, p. 151.
__
W = 184
Pd = 106, Ag = 108
__ __ __ __
__
__
__
U = 240
Ni = 59, Cu = 63
Ru = 104, Rh = 104,
J = 127
__
Bi = 208
__
__ = 100
__
Ta = 182
Fe = 56, Co = 59,
Br = 80
Te = 125
__
Pb = 207
Mn = 55
Mo = 96
__
Cl = 35.5
Se = 78
Sb = 122
__
? La = 180
F = 19
S = 32
As = 75
Sn = 118
Th = 231
O = 16
P = 31
? = 72
__
__
Hg = 200
N = 14
Ti = 48
? = 68
__
Cd = 112
( __ )
__
Al = 27.3
Zn = 65
(Ag = 108)
C = 12
? = 44
__
Ca = 40
Rb = 85
9
10
GRUPPE V
RH4
RO2
B = 11
Mg = 24
(Cu = 63)
7
8
Be = 9.4
Na = 23
5
6
RO
R2O3
GRUPPE IV
H=1
3
4
GRUPPE III
___
R2O
1
2
GRUPPE II
___
Os = 195, Ir = 197,
__
__
Pt = 198, Au = 199
__ __ __ __
Elements Properties are Predicted
Property
Mendeleev’s Predictions in 1871
Observed Properties
Scandium (Discovered in 1877)
Molar Mass
Oxide formula
Density of oxide
Solubility of oxide
44 g
M2O3
3.5 g / ml
Dissolves in acids
43.7 g
Sc2O3
3.86 g / ml
Dissolves in acids
Gallium (Discovered in 1875)
Molar mass
Density of metal
Melting temperature
Oxide formula
Solubility of oxide
68 g
6.0 g / ml
Low
M2O3
Dissolves in ammonia solution
69.4 g
5.96 g / ml
30 0C
Ga2O3
Dissolves in ammonia
Germanium (Discovered in 1886)
Molar mass
Density of metal
Color of metal
Melting temperature
Oxide formula
Density of oxide
Chloride formula
Density of chloride
Boiling temperature
of chloride
72 g
5.5 g / ml
Dark gray
High
MO2
4.7 g / ml
MCl4
1.9 g / ml
Below 100 oC
O’Connor Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 119,
71.9 g
5.47 g / ml
Grayish, white
900 0C
GeO2
4.70 g / ml
GeCl4
1.89 g / ml
86 0C
Discovering the Periodic Table
Ancient Times
Midd. -1700
1735-1843
1843-1886
H
Li
Be
1894-1918
1923-1961
Ca Sc
Rb Sr
Y
Cs Ba La
Fr
Ti
V
19
1965-
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Kr
Na Mg
K
He
1965-
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
Sn Sb Te
Hf
Tl
Pb Bi
Ta
W
Re Os
Ir
Pt Au Hg
I
Xe
Po At Rn
Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa
Journal of Chemical Education, Sept. 1989
U
Np Pu Am Cm Bk Cf Es Fm Md No Lr
Describing the Periodic Table
periodic law: the properties of elements repeat
every so often
period: horizontal row; there are 7
group (family): vertical column; there are 18
18
1
1
13 14 15 16 17
2
2
3
4
5
6
7
3 4 5 6 7 8 9 10 11 12
Dutch Periodic Table
117
116
115
114
113
112
111
110
109
108
107
106
Strong, Journal of Chemical Education, Sept. 1989, page 743
118
How to Organize Elements…
Periodic Table Designs
Regions of the Table
metals: left side of Table; form cations
properties:
lustrous
(shiny)
ductile
(can pull
into wire)
good conductors
(heat and electricity)
malleable
(can hammer
into shape)
Regions of the Table (cont.)
nonmetals: right side of Table; form anions
properties: good insulators
gases or brittle solids
neon
sulfur
iodine
bromine
Ne
S8
I2
Br2
Regions of the Table (cont.)
metalloids (semimetals): “stair” between metals
and nonmetals (B, Si, Ge, As, Sb, Te, Po)
metals
computer chips
properties: in-between those of metals
and nonmetals; “semiconductors”
Si and Ge
computer chips
alkali metals: group 1 (except H); 1+ charge;
very reactive
alkaline earth metals: group 2; 2+ charge;
less reactive than alkalis
halogens: group 17; 1– charge; very reactive
noble gases: group 18; no charge; unreactive
lanthanides: elements 58–71
actinides: elements 90–103
contain f
orbitals
coinage metals: group 11
transition elements: groups 3–12; variable charges
main block (representative) elements: groups 1, 2,
13–18
actinides
alkali metals
alkaline earth metals
coinage metals
halogens
transition elements
metalloids
noble gases
lanthanides
main block elements
more nonmetals
hydrogen
more metals
Same number of valence e– = similar properties
Li 1s2 2s1
Na 1s2 2s2 2p6 3s1
In any group, the element BELOW has one more
occupied energy level than does the element ABOVE.
Li
Na
The period that an element is in, is the same as the
energy level that its valence electrons are in.
in 2nd period
in 3rd period
Li
Na
v.e– in 2nd E.L.
v.e– in 3rd E.L.
Periodicity
there are trends in properties of elements
-- left-right AND up-down trends
atomic radius: the size of a neutral atom
…increases as we go
WHY? add a new energy
level each time
…decreases as we go
WHY? it has to do with…
coulombic attraction: attraction between (+) and (–)
Coulombic attraction depends on…
amount of charge
2+
2–
1+
1–
distance between charges
2+
2+
–
+
H
He
+
+ +
–
– –
2–
2–
As we go
,
more coulombic
attraction, no new
energy level, more
pull, smaller size
Atomic Radii of Representative Elements (nm)
1A
2A
3A
4A
5A
6A
7A
Li
Be
B
C
N
O
F
0.088
0.077
0.070
0.066
0.064
Si
P
S
Cl
0.152
0.111
Na
Mg
0.186
0.160
0.143
0.117
0.110
0.104
0.099
Ca
Ga
Ge
As
Se
Br
0.197
0.122
0.122
0.121
0.117
0.114
Rb
Sr
In
Sn
Sb
Te
I
0.244
0.215
0.162
0.140
0.141
0.137
0.133
Cs
Ba
Tl
Pb
Bi
Po
0.262
0.217
0.171
0.175
0.146
0.140
K
0.231
Al
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 175
At
0.140
shielding effect: kernel e– “shield” valence e–
from attractive force of the nucleus
v.e–
v.e–
K
Li
tougher to
remove
easier
to remove
-- caused by kernel and valence e–
repelling each other
As we go
, shielding effect increases
ionic radius: the size of an ion
cations
Ca atom
anions
Ca2+ ion
Cl atom
Cl– ion
20 p+
20 p+
17 p+
17 p+
20 e–
18 e–
17 e–
18 e–
Cl
Cl–
Ca
Ca2+
cations are smaller
anions are larger
Atomic
Ionic Radii
Radii
IA
IIA
IIIA
IVA
Li1+
Li
VA
VIA
Be2+
Be
B
C
NN3-
OO2-
F1F
1.52
0.60
1.11
0.31
0.88
0.77
0.70
1.71
0.66
1.40
0.64
1.36
1+
Na
Na
Mg2+
Mg
Al3+
Al
Si
P
1.43
0.50
1.17
1.10
1.04
1.84
0.99
1.81
2SS
VIIA
1ClCl
1.86
0.95
1.60
0.65
K
K1+
Ca
Ca2+
Ga3+
Ge
As
Se2Se
Br1Br
2.31
1.33
1.97
0.99
1.22
0.62
1.22
1.21
1.17
1.98
1.14
1.85
Rb
Rb1+
Sr
Sr2+
In3+
In
Sn
Sb
2.44
1.48
2.15
1.13
1.62
0.81
1.40
1.41
Tl3+
Tl
Pb
Bi
1.71
0.95
1.75
1.46
Cs
Cs1+
Ba
Ba2+
2.62
1.69
2.17
1.35
2TeTe
1.37
2.21
II1-
1.33
2.16
= 1 Angstrom
or 10-10 m
ionization energy: the energy required to remove
an e– from an atom
*M = metal
M + 1st I.E.
removes 1st e–
M+ + e–
M+ + 2nd I.E.
M2+ + e–
M2+ + 3rd I.E.
M3+ + e–
Each successive ionization requires
more energy than the previous one.
As we go , 1st I.E…. decreases.
(due to the shielding effect)
As we go
, 1st I.E…. increases.
Ionization Energies (kJ/mol)
Element
1st
2nd
3rd
4th
5th
6th
Na
498
4560
6910
9540
13,400
16,600
Mg
736
1445
7730
10,600
13,600
18,000
Al
577
1815
2740
11,600
15,000
18,310
Si
787
1575
3220
4350
16,100
19,800
P
1063
1890
2905
4950
6270
21,200
S
1000
2260
3375
4565
6950
8490
Cl
1255
2295
3850
5160
6560
9360
Ar
1519
2665
3945
5770
7320
8780
Herron, Frank, Sarquis, Sarquis, Cchrader, Kulka, Chemistry 1996, Heath, page
Shaded area on table denotes core electrons.
Ionization Energies of the First 20 Elements
16
14
Energy ((kJ/mol x 10–3)
12
10
1st IE
8
2nd IE
3rd IE
6
4
2
0
H
He
Li
Be
B
C
N
O
F
Ne
Na
Element
Mg
Al
Si
P
S
Cl
Ar
K
Ca
electronegativity: the tendency for
a bonded atom to
attract e– to itself
Linus Pauling quantified
the electronegativity scale
As we go , electronegativity… decreases
As we go
, electronegativity… increases
Fluorine
is the
most
electronegative
element
Electronegativities
1A
1
Period
2
3
4
5
6
7
8A
H
2.1
2A
3A
4A
5A
6A
7A
Li
Be
B
C
N
O
F
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Al
Si
P
S
Cl
1.5
1.8
2.1
2.5
3.0
Na Mg
1.2
3B
4B
5B
6B
K
Ca Sc
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
0.8
1.0
1.3
1.5
1.6
1.6
1.7
1.6
1.8
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
Sn Sb Te
0.8
1.2
1.4
1.6
1.8
1.9
2.2
2.2
2.2
1.7
1.7
1.8
Cs Ba
La*
Hf
Ta
W
Re Os
Ir
Pt Au Hg
Tl
Pb Bi
Po At
0.7
1.1
1.3
1.5
1.7
1.9
2.2
2.2
1.8
1.8
2.0
1.0
0.9
y
Fr
Ra Ac
0.7
0.9
1.1
8B
7B
1.5
1.8
2.2
1.8
1B
2B
0.9
1.8
1.9
1.9
2.4
1.9
2.0
1.9
1.9
2.4
2.1
* Lanthanides: 1.1 - 1.3
yActinides:
1.3 - 1.5
Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 373
Below 1.0
2.0 - 2.4
1.0 - 1.4
2.5 - 2.9
1.5 - 1.9
3.0 - 4.0
2.8
I
2.5
2.2