Which principle explains the order in which atomic orbitals are filled?

A. Hund's Rule

B. Pauli Exclusion Principle

C. Aufbau Principle

D. Heisenberg Uncertainty Principle

Which of the following elements has an electron configuration exception?

A. Iron

B. Chromium

C. Zinc

D. Nickel

How many unpaired electrons are present in the ground state of oxygen?

A. 1

B. 2

C. 3

D. 4

Which rule states that electrons will fill degenerate orbitals singly before pairing up?

A. Pauli Exclusion Principle

B. Hund's Rule

C. Aufbau Principle

D. Heisenberg Uncertainty Principle

Which of the following is NOT a valid representation of electron configurations using arrows?

A. ↑↓ ↑↓ ↑↓ ↑

B. ↑↓ ↑↓ ↑ ↑

C. ↑↓ ↑↓ ↑↓ ↑↓

D. ↑↓ ↑↓ ↑↓ ↓↑

a) Explain the Aufbau principle and its significance in determining the order in which atomic orbitals are filled. [3]

b) Using the Aufbau principle, determine the electron configuration for an atom with an atomic number of 11. [2]

a) Define the Pauli Exclusion Principle and explain its implications for electron filling in orbitals. [3]

b) How does the Pauli Exclusion Principle dictate electron spin in an orbital? [2]

a) Describe how electron configurations can be represented using arrows. [2]

b) What is the significance of using arrow representations in visualising electron arrangements in orbitals? [3]

a) What is Hund's rule and how does it affect the filling of electrons in degenerate orbitals? [3]

b) Using Hund's rule, describe the electron configuration of oxygen. [2]

c) Why is it energetically favourable for electrons to occupy separate degenerate orbitals before pairing up? [2]

a) How can the electron configuration of an element help in predicting its chemical properties? [3]

b) Explain the electron configuration of chromium and why it's an exception to the general rules. [3]

c) Why do some elements like chromium have unexpected electron configurations? [2]