Question 13 - Past Year - 3 Mark Questions - Chapter 5 Class 10 - Periodic Classification of Elements (Term 2)

Define groups in the Modern Periodic Table. How do valency, atomic size and metallic character vary in a group?

Answer

Groups are the vertical columns present in the modern periodic table which consists of elements having similar chemical properties .

Example: Group 1 - alkali metals

• Valency

In a group, all elements have the same valency. Eg all members of group 1 elements (alkali metals) are monovalent.

• Atomic size

As we move down the group, the number of shells increases and therefore, the atomic size also increases.

•   Metallic character: 

1. For metals: As we move down the group, metals become more reactive . This is because as atomic size increases, the strength with which electrons are held by the nucleus decreases so it becomes easier for the atom to lose electrons.
2. For non metals: As we move down the group, the ability to accept electrons decreases because of decreased electrostatic force. So, the non metallic character decreases.