L6 - Electronic Configuration of the Atom (2)

Question 1

State Heisenberg’s Uncertainty Principle.

Answer 1

“You cannot determine the position and momentum of an electron at the same time.”

Question 2

State The Aufbau Principle.

Answer 2

“Electrons enter the lowest available energy level first.”

Question 3

State Hund’s Rule of Maximum Multiplicity.

Answer 3

“When in orbitals of equal energy, electrons will try to remain unpaired.”

(Minimises repulsion between like charges, so the system is more stable).

Question 4

State the Pauli Exclusion Principle.

Answer 4

“No two electrons can have the same four quantum numbers.”

“Only 2 electrons can go in each orbital, provided they are of opposite spins.”

Question 5

Describe the spacing of energy levels.

Answer 5

• Energy levels are not equally spaced

- They get closer together further from the nucleus

Question 6

Describe some special cases with regards to the filling of orbitals.

Answer 6

In some elements the 4s orbital is filled before the 3d orbital:

• Chromium: (Z=24)
• Copper: (Z=29)

Question 7

Describe the electronic configuration of ions.

Answer 7

• Positive ions (cations) are formed by removing electrons from atoms
• Negative ions (anions) are formed by adding electrons to atoms

Question 8

Electrons are removed first from the ________ ________ ________. What is an exception to this rule?

Answer 8

• Electrons are removed first from the highest occupied orbitals
• Except transition metals

Question 9

What does a large jump between successive ionisation energy indicate? And what does this provide evidence of?

Answer 9

• A change in energy level from which the electron has been removed.
• Gives evidence of shells.

Question 10

What contrast agent is used in MRI scanning image enhancement?

Answer 10

Gd3+ is commonly used (7 unpaired electrons)

Question 11

What does an MRI show?

Answer 11

The magnetic environment of every hydrogen atom being scanned.

Question 12

What do contrast agents allow for?

Answer 12

Easier interpretation

Question 13

What does Madelung’s Rule predict?

Answer 13

That energy increases with (n + l), then with n for identical values of (n+l).

Question 14

What is the best ion for use in compounding an MRI contrast agent?

Answer 14

Fe3+

Question 15

What does electron affinity depend on?

Answer 15

• Attraction of electrons to the nucleus

- Electron-electron repulsion