Group  
  I II   III IV V VI VII VIII  
1
1
H
 
2
He
 
2
3
Li
4
Be
 
5
B
6
C
7
N
8
O
9
F
10
Ne
 
3
11
Na
12
Mg
 
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
 
4
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
 
5
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
 
6
55
Cs
56
Ba
57
La
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
 
7
87
Fr
88
Ra
89
Ac
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
   

58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr

 
 


Periodic Table was first discovered in 1869 by Dmitry Mendeleyev. The elements are arranged in an increasing order of their atomic numbers as one goes from left to right accross the table. The horizontal rows are called periods and the columns are called groups.
A noble gas is found at the right hand side of each period. There is a progression from metals to non-metals across each period. Elements found in groups (e.g. alkali, halogens) have a similar electronic configuration. The number of electrons in outer shell is the same as the number of the group (e.g. lithium 21).
The block of elements between groups II and III are called transition metals. These are similar in many ways; they produce colored compounds, have variable valency and are often used as catalysts. Elements 58 to 71 are known as lanthanide or rare earth elements. These elements are found on earth in only very small amounts.
Elements 90 to 103 are known as the actinide elements. They include most of the will known elements which are found in nuclear reactions. The elements with larger atomic numbers than 92 do not occur naturally. They have all been produced artificially by bombarding other elements with particles.

 

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