Mendeleevs Classification
Category : 10th Class
In 1869, a Russian chemist, Mendeleev, on the basis of physical and chemical properties discovered a relation known as "PERIODIC LAW". "The properties of element are the periodic function of their atomic masses".
Group |
I |
II |
III |
IV |
V |
VI |
VII |
VIII |
Oxide Hydride |
R2O RH |
RO RH2 |
R2O3 RH3 |
RO2 RH4 |
R2O5 RH3 |
RO3 RH2 |
R2O7 RH |
RO4 |
Periods ¯ |
A B |
A B |
A B |
A B |
A B |
A B |
A B |
Transition Series |
1 |
H 1.008 |
|
|
|
|
|
|
|
2 |
Li 6.939 |
Be 9.012 |
B 10.81 |
C 12.011 |
N 14.004 |
O 15.999 |
F 18.998 |
|
3 |
Na 22.99 |
Mg 24.31 |
Al 29.98 |
Si 28.09 |
P 30.974 |
S 32.06 |
Cl 35.453 |
|
4 First Series Second Series |
K 39.102 Cu 63.54 |
C 40.08 Zn 65.37 |
Sc 44.96 Ga 69.72 |
Ti 47.90 Ge 72.59 |
V 50.94 As 74.92 |
Cr 50.20 Se 78.96 |
Mn 54.94 Br 79.909 |
Fe 55.85 Co 58.93 Ni 58.71 |
5 First Series Second Series |
Rb 85.47 Ag 107.87 |
Sr 87.62 Cd 112.40 |
Y 88.91 In 114.82 |
Zr 91.22 Sn 118.69 |
Nb 92.91 Sb 121.75 |
Mo 95.94 Te 127.60 |
Te 99 I 126.90 |
Ru 101.07 Rh 102.91 Pd 106.4 |
6 First Series Second Series |
Cs 132.90 Au 196.97 |
Ba 137.34 Hg 200.59 |
La 138.91 Ti 204.37 |
Hf 178.49 Pb 207.19 |
Ta 180.95 Bi 208.98 |
W 183.85
|
|
Fe 190.2 Co 192.2 Ni 195.09 |
Mendeleev arranged the known elements according to increasing order of their atomic masses. According to him, the fundamental property of an element was atomic mass. He arranged these elements into eight groups and then further divided into subgroups.
Merits of Mendeleev’s Periodic Table
Mendeleev's periodic table offered the following advantages in understanding the properties of elements.
Demerits in Mendleev's Periodic Table
Hence it is not possible to predict the number of missing elements by knowing the atomic masses of two known elements.
According to Newland's how many elements are there in nature?
(a) 20
(b) 25
(c) 30
(d) 56
(e) None of these
Answer: (d)
What was the basis of Mendeleev's classification?
(a) Atomic Mass
(b) Atomic Number
(c) Valency
(d) Isotopes
(e) None of these
Answer: (a)
In which year Mendeleev's formulated the law of classification?
(a) 1865
(b) 1870
(c) 1869
(d) 1875
(e) None of these
Answer: (C)
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