Newlands proposed the law of octaves . Mendeleeff suggested eight groups for elements in his table . How do you explain these observations in terms of modern periodic classification ?

How do you appreciate the role of electronic configuration of the atoms of elements in periodic classification ?

How do you appreciate Dobereiner for his efferts in the classification of elements ?

How does atomic radius vary in a period and in a group? How do you explain the variation.

How does atomic radius vary in a period and in a group? How do you explain the variation?

Do you know why Newlands proposed the law of octaves ? Explain your answer in terms of the modern structure of the atom .

(i) Newlands proposed the law of octaves. ii) The law of octaves was not valid for elements that had atomic masses higher than calcium. iii) Newlands left blanks for new elements in his periodic table. Which statement is wrong?

How do you appreciate Mendeleeff for his great contribution in the prepartion of modern periodic table ?

Explain the similarities between the Newlands. Mendeleeff and modern periodic table.