Chemistry Reference
In-Depth Information
The success of Mendeleev's predictions showed
that his ideas were probably correct. His periodic
table was quickly accepted by scientists as an
important summary of the properties of the elements.
Mendeleev's periodic table has been modified in the
light of work carried out by Rutherford and Moseley.
Discoveries about sub-atomic particles led them to
realise that the elements should be arranged by proton
number. In the modern Periodic Table the 118 known
elements are arranged in order of increasing proton
number (Figure 9.3). Those elements with similar
chemical properties are found in the same columns or
groups
. There are eight groups of elements. The first
column is called Group I; the second Group II; and so
on up to Group VII. The final column in the Periodic
Table is called Group 0 (or Group VIII). Some of the
groups have been given names.
Group I: The alkali metals
Group II: The alkaline earth metals
Group VII: The halogens
Group 0:
Period
Group
1
2
3
4
5
6
7
8
H
1
Li
Be
B
C
NOF
2
Na
Mg
Al
Si
P
S
Cl
3
K
Ca
*
Ti
V
Cr
Mn
Fe Co Ni
4
Cu
Zn
*
†
As
Se
Br
Figure 9.2
Mendeleev's periodic table. He left gaps for undiscovered
elements.
In 1886 the element we now know as germanium
was discovered in Germany by Clemens Winkler; its
properties were almost exactly those Mendeleev had
predicted. In all, Mendeleev predicted the atomic
weight of ten new elements, of which seven were
eventually discovered - the other three, atomic
weights 45, 146 and 175, do not exist!
Inert gases or noble gases
0
Period
Group
H
He
1
1
Hydrogen
4
2
Helium
1
I
II
III
IVVVI
VII
Li
Be
11
5
B
12
6
C
14
7
Nitrogen
N
16
8
Oxygen
O
19
9
Fluorine
F
20
10
Ne
7
3
Lithium
Na
9
4
Beryllium
2
Boron
Carbon
Neon
Ar
Mg
Al
Si
P
S
Cl
23
11
Sodium
K
24
12
Magnesium
27
13
Aluminium
28
14
31
15
Phosphorus
32
16
35.5
17
Chlorine
40
18
Argon
Kr
3
Silicon
Sulfur
39
19
Potassium
Rb
40
20
Calcium
Ca
45
21
Scandium
Sc
48
22
Titanium
Ti
51
23
Vanadium
V
52
24
Chromium
Cr
55
25
Manganese
Mn
56
26
Fe
59
27
Co
59
28
Ni
63.5
29
Copper
Cu
65
30
Zn
Ga
73
32
Germanium
Ge
75
33
Arsenic
As
79
34
Selenium
Se
80
35
Bromine
Br
84
36
Krypton
Xe
70
31
Gallium
4
Iron
Cobalt
Nickel
Zinc
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
85
37
Rubidium
Cs
88
38
Strontium
89
39
Yttrium
91
40
Zirconium
93
41
Niobium
96
42
Molybdenum
99
43
Technetium
101
44
Ruthenium
103
45
Rhodium
106
46
Palladium
108
47
112
48
Cadmium
115
49
Indium
119
50
122
51
Antimony
Bi
128
52
Tellurium
127
53
Iodine
131
54
Xenon
5
Silver
Tin
Ba
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Po
At
Rn
133
55
Caesium
Fr
137
56
Barium
Ra
178.5
72
Hafnium
181
73
Tantalum
184
74
Tungsten
186
75
Rhenium
190
76
Osmium
192
77
Iridium
195
78
Platinum
197
79
201
80
Mercury
204
81
Thallium
207
82
209
83
Bismuth
209
84
Polonium
210
85
Astatine
222
86
Radon
6
Gold
Lead
223
87
Francium
226
88
Radium
261
Rf
262
Db
263
Sg
262
Bh
269
Hs
268
Mt
281
Ds
272
Rg
285
Cn
284
Uut
285
Fl
288
Uup
292
Lv
Uus
293
Uno
7
104
Rutherfordium
105
Dubnium
106
Seaborgium
107
Bohrium
108
Hassium
109
Meitnerium
110
Darmstadtium
111
Roentgenium
112
Copernicium
113
Ununtrium
114
Flerovium
115
Ununpentium
116
Livermorium Ununseptium
117
118
Ununoctium
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
139
57
Lanthanum
140
58
Cerium
141
59
Praseodymium
144
60
Neodymium
147
61
Promethium
150
62
Samarium
152
63
Europium
157
64
Gadolinium
159
65
Terbium
162
66
Dysprosium
165
67
Holmium
Es
167
68
Erbium
169
69
Thulium
173
70
Ytterbium
175
71
Lutetium
Lr
227
89
Actinium
Ac
232
90
Thorium
Th
231
91
Protactinium
Pa
238
92
Uranium
U
237
93
Neptunium
Np
244
94
Plutonium
Pu
243
95
Americium
Am
247
96
Curium
Cm
247
97
Berkelium
Bk
251
98
Californium
Cf
252
99
Einsteinium
257
100
Fermium
Fm
258
101
Mendelevium
Md
259
102
Nobelium
No
260
103
Lawrencium
Key
reactive metals
transition metals
poor metals
metalloids
non-metals
noble gases
Figure 9.3
The modern Periodic Table.
