Valence Electrons and Electron Configurations

The video tutorial explains exceptions in electron configurations, focusing on chromium and copper. It discusses Hund's rule and the stability of half-filled orbitals. The tutorial also covers transition metals and their variable oxidation states, highlighting the complexity of their electron configurations. Finally, it emphasizes the role of valence electrons in chemical reactions, explaining how they are shielded by core electrons and are crucial in bonding and redox reactions.

What does Hund's rule state about electron configuration?

• The most stable configuration has the maximum number of unpaired electrons.

• Electrons prefer to pair up in orbitals.

• Electrons fill the lowest energy orbitals first.

• Electrons fill orbitals in a random order.

Why are half-filled orbitals considered more stable?

• They are closer to the nucleus.

• They contain more electrons than fully filled orbitals.

• All electron spins are aligned, creating a consistent magnetic moment.

• They have lower energy levels.

What is the observed electron configuration for chromium?

• [Ar] 4s1 3d4

• [Ar] 4s2 3d5

• [Ar] 4s1 3d5

• [Ar] 4s2 3d4

Which elements share a similar electron configuration exception with chromium?

• Copper and Zinc

• Iron and Nickel

• Molybdenum and Tungsten

• Silver and Gold

What is the unique electron configuration observed for copper?

• [Ar] 4s2 3d9

• [Ar] 4s2 3d10

• [Ar] 4s1 3d10

• [Ar] 4s1 3d9

Why do copper, silver, and gold have unique electron configurations?

• They have a full outer shell.

• They have fewer electrons than expected.

• They are noble gases.

• Their 3d and 4s energy levels switch, leading to stability.

What is the primary role of valence electrons in chemistry?

• They are difficult to remove due to high kinetic energy.

• They are involved in chemical bonding and reactions.

• They are buried deep within the atom.

• They determine the atomic mass.

How are valence electrons shielded from the nucleus?

• By the atomic mass.

• By the outer shell.

• By the core electrons.

• By other valence electrons.

What makes core electrons difficult to remove?

• They have high potential energy.

• They are involved in chemical reactions.

• They have high kinetic energy and are buried deep within the atom.

• They are in the outermost shell.

Which electrons are primarily exchanged in redox reactions?

• Inner shell electrons

• Valence electrons

• Core electrons

• Noble gas electrons