question_answer

Write the number of periods and groups in the Modern Periodic Table. How does the metallic character of elements vary on moving (i) from left to right in a period, and (ii) down a group? Give reason to justify your answer.

Answer:

In the modern periodic table, there are 18 vertical columns known as Groups and 7 horizontal rows known as Periods.

Metallic character: It is defined as the tendency of an atom to lose electrons. Across the period i.e. from left to right, metallic character decreases. Down the group i.e., from top to bottom, metallic character increases.

Reason: Across the period, the effective nuclear charge increases, thus decreasing its atomic radius. This favours the electronegativity and therefore the tendency to lose electrons is low. This accounts for the decrease in the metallic character. As we move down the group, the number of shells keep on increasing and therefore the atomic size increases and electronegativity decreases. This enhances the ability to lose electrons and therefore the metallic character increases.