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Modern Periodic Table

 

In 1913 Henry Moseley, a British chemist proposed that atomic number can be used as the organizing principle instead of atomic mass.
 

Henry Mosley


The basis of the modern periodic table is Moseley's Periodic Law according to which the properties of elements are a periodic function of their atomic numbers. This means that if the elements are arranged in order of their increasing atomic number, then elements with similar properties are repeated after a regular interval.

The modern periodic law is based on the atomic number as the fundamental property in contrast to atomic weight (mass) as in the case of Mendeleev's periodic law. The atomic number of an element is equal to the number of protons in the nucleus of its atom. Atomic number is also equal to the number of electrons in an atom.

 

The long form of periodic table is known as the Modern Periodic Table. The modern periodic table is based on Moseley's periodic law. The modern periodic table has seven horizontal rows of elements which are called periods or rows. Periods do not have the same number of elements as some periods are short while others are long.
 

 The Modern Periodic Table

Group

s-Block

 

p - block

Period

 

 

 

1

H
1

 


 

 

H
1

He
2

2

Li
3

Be
4

 {--------------------   d- Block -----------------}

B
5

C
6

N
7

O
8

F
9

Ne
10

3

Na
11

Mg
12

Al
13

Si
14

P
15

S
16

Cl
17

Ar
18

4

K
19

Ca
20

Sc
21

Ti
22

V
23

Cr
24

Mn
25

Fe
26

Co
27

Ni
28

Cu
29

Zn
30

Ga
31

Ge
32

As
33

Se
34

Br
35

Kr
36

5

Rb
37

Sr
38

Y
39

Zr
40

Nb
41

Mo
42

Tc
43

Ru
44

Rh
45

Pd
46

Ag
47

Cd
48

In
49

Sn
50

Sb
51

Te
52

I
53

Xe
54

6

Cs
55

Ba
56

La
57

Hf
72

Ta
73

W
74

Re
75

Os
76

Ir
77

Pt
78

Au
79

Hg
80

Tl
81

Pb
82

Bi
83

Po
84

At
85

Rn
86

7

Fr
87

Ra
88

Ac
89

Ku
104

Hh
105

 

f-block

Lantha
nides->

Ce
58

Pr
59

Nd
60

Pm
61

Sm
62

Eu
63

Gd
64

Tb
65

Dy
66

Ho
67

Er
68

Tm
69

Yb
70

Lu
71

 

Actini
des->

Th
90

Pa
91

U
92

Np
93

Pu
94

Am
95

Cm
96

Bk
97

Cf
98

Es
99

Fm
100

Md
101

No
102

Lr
103

 

The Modern Periodic Table


The Modern Periodic table has 18 vertical columns known as groups and 7 horizontal rows known as periods.





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