Q1. Writing Electron Configurations

Background

Topic: Atomic Structure & Electron Arrangement

This topic tests your understanding of how electrons are distributed in an atom's orbitals, following the rules of quantum mechanics and the periodic table.

Key Terms and Formulas:

• Electron configuration: The notation showing the arrangement of electrons in an atom's orbitals.

• Aufbau Principle: Electrons fill the lowest energy orbitals first.

• Pauli Exclusion Principle: Each orbital can hold a maximum of two electrons with opposite spins.

• Hund's Rule: Electrons occupy orbitals singly before pairing up.

Step-by-Step Guidance

1. Identify the atomic number of the element to determine the total number of electrons.

2. List the order of orbital filling using the periodic table or the diagonal rule (1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.).

3. Assign electrons to each orbital, following the Aufbau Principle, Pauli Exclusion Principle, and Hund's Rule.

4. Write the electron configuration in standard notation (e.g., ).

Try solving on your own before revealing the answer!

Q2. Heat of Fusion and/or Heat of Vaporization Problems

Background

Topic: Thermochemistry & Phase Changes

This topic tests your ability to calculate the energy required for a substance to change phase (solid to liquid or liquid to gas) using heat of fusion or heat of vaporization.

Key Terms and Formulas:

• Heat of fusion (): Energy required to melt 1 gram or 1 mole of a substance.

• Heat of vaporization (): Energy required to vaporize 1 gram or 1 mole of a substance.

• Formula:

• Where = heat absorbed/released, = mass, = heat of fusion or vaporization.

Step-by-Step Guidance

1. Identify the mass of the substance undergoing the phase change.

2. Determine whether the process is melting (fusion) or vaporization.

3. Find the appropriate heat of fusion or vaporization value (usually given in the problem or a table).

4. Set up the formula and plug in the known values.

Try solving on your own before revealing the answer!

Q3. Specific Heat Problems

Background

Topic: Thermochemistry & Heat Transfer

This topic tests your ability to calculate the amount of heat required to change the temperature of a substance using its specific heat capacity.

Key Terms and Formulas:

• Specific heat (): The amount of heat needed to raise the temperature of 1 gram of a substance by 1°C.

• Formula:

• Where = heat absorbed/released, = mass, = specific heat, = change in temperature.

Step-by-Step Guidance

1. Identify the mass of the substance and its specific heat value.

2. Determine the initial and final temperatures to calculate ().

3. Set up the formula and plug in the known values.

Try solving on your own before revealing the answer!