Embibe Experts Solutions for Chapter: Periodic Classification of Elements, Exercise 1: CBSE-2019

The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.

List any three observations which posed a challenge to Mendeleev’s Periodic law.

How does the metallic character of elements vary on moving from left to right in a period? Give a reason for your answer.

How does the metallic character of elements vary on moving from top to bottom in a group of the Modern Periodic Table? Give a reason for your answer.

The electrons in the atoms of four elements A, B, C and D are distributed in three shells having $1, 3, 5$ and $7$, electrons respectively in their outermost shells. Write the group numbers in which these elements are placed in the Modern Periodic Table. Write the electronic configuration of the atoms of B and D, and the molecular formula of the compound formed when B and D combine.

Define atomic size. Give its unit of measurement. In the modern periodic table what trend is observed in the atomic radius in a group and a period, and why is it so?

State Newlands law of Octaves.