Electron Configuration Exceptions and more definitions

Question 1

Aufbau Principle

Answer 1

electrons fill orbitals from ground up, electrons must be at the lowest possible energy level

Question 2

energy-level diagrams

Answer 2

Relative energies of the electrons in an atom

Question 3

Hund’s Rule

Answer 3

electrons fill orbitals where no pairs are put into orbitals unless necessary, they will first occupy empty orbitals b4 pairing

Question 4

Pauli Exclusion Principle

Answer 4

unpaired electrons have parallel spins, and no 2 electrons in an atom have the same quantum numbers

Question 5

What are the 2 exceptions to the Aufbau Principle?

Answer 5

Electron configuration of Chromium and Copper (would also happen to Molybdenum, below Chromium)

Why?
- unfilled substances are less stable than half and fully filled substances
- unfilled substances have greater energy

In the case of Copper, its more stable for the electron in 3d to move to 4s which goes against the Aufbau principle

Question 6

REVIEW: WHY IS COPPER AN EXCEPTION TO THE AUFBAU PRINCIPLE

Answer 6

Copper is an exception because a filled “d” sub shell is more stable than a full “s”, therefore, an electron moves from the “s” sub shell to the “d” sub shell

THEREFORE, IF THERE IS A FULL S BLOCK AND AN UNFILLED D BLOCK THEN ITS AN EXCEPTION

Question 7

Which elements are exceptions to the aufbau principle?

Answer 7

Copper, Chromium, and Silver

Question 8

copper and chromium electron configuration ending

Answer 8

COPPER: 4s ^ 1
3d ^ 10

CHROMIUM: 4s ^ 1
3d ^ 5