Question

Why are 8 elements placed in the third period of modern periodic table?

Answer 1

According to the Aufbau's Principle (the building up principle) there can be only EIGHT elements that satisfy this. This is because the S orbital of the fourth shell sits at a lower energy level (closer to the nucleus) than the d orbital of the thirdshell.

Answer 2

Heya !

Here is your answer :


1. sodium

2. magnesium

3. aluminium

4. silicon

5. phosphorus

6. sulphur

7. chlorine

8. argon