Question

most important topics from periodic classification of elements...

Dont spAm​

Answer 1

Answer =Following are the two observations which posed a challenge to Mendeleev's Periodic Law. (i) Increasing order of atomic weights could not be maintained while matching chemical properties. Chemical properties do not depend upon atomic mass. (ii) Isotopes have different atomic mass but same chemical properties.

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Answer 2

Hola

Important topics of periodic table are:

• All the laws
• Dobereiner’s Triads
• Newlands’ Law of Octaves
• Lother Meyer’s Law
• Mendeleev’s Periodic Law
• Long Form of the Periodic Table
• Periodicity
• Variation of Periodic Properties in the Periodic Table
• Learn all the trends of the modern periodic table.

PERIODIC CLASSIFICATION OF ELEMENTS

HOTS

1. On what basis did Mendeleev classified the element?
2. Define ‘groups and period’?
3. What is common among all the elements present in one period?
4. Name two alkali metals present in Group 1.
5. An element X belongs to II group and 2nd period. Write atomic number and name of element.
6. The electronic configuration of an atom is 2,8,7. Give its atomic number, nature of oxide.
7. Why are noble gases placed in a separate group?
8. Lithium, sodium potassium belong to same group called alkali metals. Why?
9. Give characteristics of period.
10. State three points of difference between Mendeleev’s Periodic Table and Modern Periodic Table.