Periodic Trends and Electron Configuration

The video tutorial covers the periodic classification of elements for class 10 students. It explains how atomic radius decreases across a period due to increasing nuclear charge, leading to a decrease in metallic character. The video also discusses how elements in the same group have the same valency due to similar valence electron configurations. Additionally, it explains why the third period contains only eight elements despite having a higher electron capacity. The tutorial aims to provide a clear understanding of these scientific concepts.

What happens to the atomic radius as you move from left to right across a period?

• It fluctuates randomly.

• It remains the same.

• It decreases.

• It increases.

Why does the atomic radius decrease across a period?

• Because the number of protons decreases.

• Because the nuclear charge increases.

• Because the nuclear charge decreases.

• Because the number of shells increases.

What trend is observed in metallic character as you move across a period?

• It increases.

• It decreases.

• It remains constant.

• It becomes unpredictable.

As you move from left to right in a period, what happens to the non-metallic character?

• It decreases.

• It increases.

• It disappears.

• It remains unchanged.

What determines the valency of an element?

• The number of valence electrons.

• The number of protons.

• The number of neutrons.

• The atomic mass.

Why do elements in the same group have the same valency?

• They have the same atomic number.

• They have the same number of valence electrons.

• They have the same number of neutrons.

• They have the same atomic mass.

Which group of elements is known as alkali metals?

• Group 2

• Group 1

• Group 18

• Group 17

How many elements are there in the third period?

• 18

• 10

• 8

• 12

Why does the third period contain only eight elements?

• Because the third shell is unstable.

• Because the electron capacity of the third shell is 18.

• Because the third shell can only hold 8 electrons.

• Because electrons start filling the fourth shell.

What is the electron capacity of the third shell?

• 12

• 18

• 8

• 10