Electron Configuration Stability Concepts

The video tutorial discusses exceptions in electron configurations, focusing on chromium and copper. Chromium, with 24 electrons, typically has a configuration of 1s2 2s2 2p6 3s2 3p6 4s2 3d4, but it is more stable as 4s1 3d5. Similarly, copper, with a configuration of 1s2 2s2 2p6 3s2 3p6 4s2 3d9, is more stable as 4s1 3d10. These exceptions occur because half-filled and fully filled d orbitals are more stable.

What is the main focus of the video tutorial?

• The periodic table

• Exceptions in electron configurations

• The history of electron configurations

• Basic principles of chemistry

How many electrons does chromium have?

• 24

• 25

• 23

• 22

What is the expected electron configuration for chromium before adjustment?

• 1s2 2s2 2p6 3s2 3p6 4s2 3d4

• 1s2 2s2 2p6 3s2 3p6 4s2 3d5

• 1s2 2s2 2p6 3s2 3p6 4s1 3d4

• 1s2 2s2 2p6 3s2 3p6 4s1 3d5

Why is the 3d5 configuration more stable for chromium?

• It is half-filled

• It is fully filled

• It has more electrons

• It is empty

What is the electron configuration for copper before adjustment?

• 1s2 2s2 2p6 3s2 3p6 4s2 3d9

• 1s2 2s2 2p6 3s2 3p6 4s1 3d9

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10

• 1s2 2s2 2p6 3s2 3p6 4s1 3d10

What change is made to copper's electron configuration for stability?

• An electron is removed from the 3d orbital

• An electron is added to the 4s orbital

• An electron is moved from the 4s to the 3d orbital

• An electron is moved from the 3d to the 4s orbital

What is the final electron configuration for copper after adjustment?

• 1s2 2s2 2p6 3s2 3p6 4s1 3d9

• 1s2 2s2 2p6 3s2 3p6 4s2 3d9

• 1s2 2s2 2p6 3s2 3p6 4s1 3d10

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10

Why is a fully filled d sublevel considered stable?

• It is less reactive

• It has the highest energy

• It is more reactive

• It has the lowest energy

Which of the following is NOT a reason for electron configuration exceptions?

• Energy minimization

• Stability of fully filled orbitals

• Random electron movement

• Stability of half-filled orbitals

What is the main takeaway regarding electron configuration exceptions?

• They are random and unpredictable

• They occur only in noble gases

• They are irrelevant to chemical reactions

• They are based on stability considerations