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Periodic classification of Elements

Sashank
24/12/2018 0 0

How many elements known to us?

Ans: 118

Who gave the theory of triads?

Ans: Dobereiner 

Who gave Octave theory?

Ans: Newlands

What is the drawback of Dobereiner traits?

Only three triads were recognised from the elements known at a time.

What is the drawback of Newlands Octave theory?

Ans: It applied to calcium, properties of newly discovered elements didn't fit into the law of Octave.

In Mendeleev periodic table how many periods and groups are there?

Ans: 7 periods and eight groups.

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