Chapter 11, Problem 66A

Interpretation Introduction

Interpretation: The reason for electrons in $2p$ sublevel to occupy in two different $2p$ orbital needs to be explained.

Concept introduction: This can be explained by Hund’s rule of maximum multiplicity.

According to Hund’s rule,

“Before the orbital is doubly occupied, every orbital in the sub level is singly occupied”.

Answer to Problem 66A

Electrons gets fill in two different $2p$ orbital and do not get paired up at first.

Explanation of Solution

Many unpaired electrons are present in atoms which are at the ground state. Since electrons are tiny bar magnet if two electrons come in contact they would show the same behavior as two magnets do. The electrons first try to get as far away from each other as possible before they have to pair up due to repulsion between them. Hence electron will not pair with another electron in a half-filled as long as vacant orbital of similar energy is available.

  $2p$

As obvious from orbital diagram that electrons first getting filled up in different $2p$ orbital and not getting paired up first.

Conclusion

Electrons gets fill in two different $2p$ orbital and do not get paired up at first.