Page 3 - 3. Lesson Notes Ch-5 MENDELEEVES CLASSIFICATION

 He sorted out the elements with similar properties and pinned the cards
together in a sequence, on a wall.
 He observed that most of the elements got a place in the Periodic Table
and were arranged in the order of their increasing atomic masses.

 It was also observed that there occurs a periodic recurrence of elements
with similar physical and chemical properties.

On this basis, Mendeléev formulated a Periodic Law-

 Mendeleev’s Periodic Law states that the “properties of elements are the
periodic function of their relative atomic masses.”

• Merits of Mendeleev’s Periodic Table:

1. Mendeleev left some blank spaces in his periodic table in order to place
the elements having similar properties in the same group.

For example;

a. Titanium has been placed in IVth group, leaving a blank space adjacent to
it in IIIrd group.
b. Similarly, arsenic has been placed in Vth group; leaving two adjacent
spaces blank.

These spaces have been occupied by scandium, gallium and germanium after
their subsequent discovery.

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