Physical Chemistry Overview Quiz

Physical Chemistry

Definition: The study of macroscopic and microscopic phenomena in chemical systems using the methods of physics.
Key Concepts:
- Thermodynamics:
  - Laws of Thermodynamics (Zeroth, First, Second, Third).
  - Concepts of enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG).
- Chemical Kinetics:
  - Reaction rates and factors affecting them (concentration, temperature, catalysts).
  - Rate laws and mechanisms of chemical reactions.
- Equilibrium:
  - Dynamic equilibrium in reversible reactions.
  - Le Châtelier's Principle.
  - Equilibrium constants (Kc, Kp) and their calculations.
- Electrochemistry:
  - Redox reactions and the concept of oxidation and reduction.
  - Cells (galvanic and electrolytic), Nernst equation, and standard electrode potentials.
- Spectroscopy:
  - Interaction of light with matter (absorption, emission).
  - Methods such as UV-Vis, IR, NMR, and mass spectrometry.

Atomic Structure

Basic Concepts:
- Atom: The smallest unit of matter retaining properties of an element.
- Subatomic Particles: Protons (positive charge, in nucleus), Neutrons (neutral charge, in nucleus), Electrons (negative charge, in orbitals).
Atomic Models:
- Dalton's Model: Indivisible atoms; elements consist of identical atoms.
- Thomson's Model: "Plum pudding" model with electrons in a positive "soup".
- Rutherford's Model: Nucleus at the center; electrons orbiting around it.
- Bohr's Model: Electrons in defined orbits (energy levels); quantized energy states.
Quantum Mechanics:
- Wave-Particle Duality: Electrons exhibit both wave-like and particle-like properties.
- Heisenberg Uncertainty Principle: Impossible to simultaneously know position and momentum of an electron.
- Orbitals: Probability maps for electron locations (s, p, d, f types).
Periodic Table:
- Organization by increasing atomic number; groups (columns) and periods (rows).
- Trends: Atomic radius, ionization energy, electronegativity, and electron affinity across periods and groups.
Isotopes:
- Atoms of the same element with different numbers of neutrons.
- Examples: Carbon-12 and Carbon-14; implications in dating and nuclear chemistry.

Physical Chemistry

Definition: The study of macroscopic and microscopic phenomena in chemical systems using the methods of physics.
Thermodynamics:
- Laws of Thermodynamics: Define how energy is transferred and transformed in a system.
  - Zeroth Law: If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.
  - First Law: Energy cannot be created or destroyed, only transferred or transformed.
  - Second Law: The entropy of an isolated system always increases over time.
  - Third Law: The entropy of a perfect crystal at absolute zero is zero.
- Enthalpy (ΔH): Change in heat energy during a reaction at constant pressure.
  - Endothermic: ΔH positive (absorbs heat)
  - Exothermic: ΔH negative (releases heat)
- Entropy (ΔS): Measure of disorder or randomness in a system
  - Increases with more states, higher temperature, or more volume
- Gibbs Free Energy (ΔG): Determines spontaneity of a reaction.
  - ΔG < 0 (negative): Spontaneous or exergonic
  - ΔG > 0 (positive): Non-spontaneous or endergonic
  - ΔG = 0 (zero): Equilibrium

Chemical Kinetics

Reaction Rate: The change in concentration of reactants or products over time.
- Factors affecting rate:
  - Concentration: Higher concentration, faster rate
  - Temperature: Higher temperature, faster rate
  - Catalysts: Increase rate without being consumed
Rate Laws: Mathematical expressions that relate the rate of a reaction to the concentrations of reactants.
- Rate constant (k): Proportionality constant that depends on temperature
Reaction Mechanisms: The series of elementary steps that describe how a reaction proceeds
- Elementary step: A single molecular event
- Rate-determining step: The slowest step in the mechanism; limits the overall reaction rate

Equilibrium

Dynamic Equilibrium: A state where the rates of the forward and reverse reactions are equal.
- No net change in concentration of reactants or products.
Le Châtelier's Principle: If a change of condition is applied to a system at equilibrium, the system will shift in a direction that relieves the stress.
Equilibrium Constants (Kc, Kp):
- Kc: Equilibrium constant in terms of concentrations
- Kp: Equilibrium constant in terms of partial pressures
- Larger K: Favors product formation
- Smaller K: Favors reactant formation

Electrochemistry

Redox Reactions: Involve the transfer of electrons.
- Oxidation: Loss of electrons
- Reduction: Gain of electrons
Electrochemical Cells: Devices that convert chemical energy into electrical energy or vice versa.
- Galvanic Cell: Converts chemical energy into electrical energy (spontaneous).
  - Anode: Oxidation (negative electrode)
  - Cathode: Reduction (positive electrode)
- Electrolytic Cell: Uses electrical energy to drive a non-spontaneous reaction.
  - Anode: Oxidation (positive electrode)
  - Cathode: Reduction (negative electrode)
Nernst Equation: Relates the cell potential (Ecell) to the standard cell potential (E°cell) and the concentrations of reactants and products.
Standard Electrode Potentials (E°): The potential difference between an electrode and its solution under standard conditions.
- More positive E°: Stronger oxidizing agent.
- More negative E°: Stronger reducing agent.

Spectroscopy

Interaction of Light with Matter: Light can be absorbed or emitted by molecules.
Spectroscopic Methods: Use electromagnetic radiation to identify and quantify substances.
- UV-Vis spectroscopy: Absorption of ultraviolet and visible light by molecules; reveals electronic transitions.
- IR spectroscopy: Absorption of infrared radiation by molecules; provides information about functional groups.
- NMR spectroscopy: Nuclear magnetic resonance; provides information about the structure and connectivity of molecules.
- Mass Spectrometry: Measures the mass-to-charge ratio (m/z) of ions; helps identify molecules.

Atomic Structure

Atoms: The smallest unit of matter retaining properties of an element.
Subatomic Particles:
- Protons: Positively charged, found in the nucleus.
- Neutrons: Neutrally charged, found in the nucleus.
- Electrons: Negatively charged, found in orbitals surrounding the nucleus.
Atomic Models:
- Dalton's Model (1803): Atoms are indivisible, solid spheres. Elements are made up of identical atoms.
- Thomson's Model (1897): Atoms are spheres of positively charged matter containing negatively charged electrons embedded like raisins in a plum pudding.
- Rutherford's Model (1911): Atoms have a small, dense, positively charged nucleus at their centre surrounded by a cloud of negatively charged electrons.
- Bohr's Model (1913): Electrons orbit the nucleus in specific, quantized energy levels. Electrons can jump between levels by absorbing or emitting energy.
- Quantum Mechanics (1920s): Electrons do not orbit the nucleus in a fixed path, but instead exist in regions of space called orbitals.
  - Wave-Particle Duality: Electrons exhibit both wave-like and particle-like properties.
  - Heisenberg Uncertainty Principle: It is impossible to simultaneously know the exact position and momentum of an electron.
  - Orbitals: Probability maps for electron locations (s, p, d, f types).
Periodic Table:
- Elements arranged by increasing atomic number.
- Periods (rows): Elements with the same number of electron shells.
- Groups (columns): Elements with the same number of valence electrons, resulting in similar chemical properties.
- Trends:
  - Atomic Radius: Decreases across a period (due to increasing nuclear charge) and increases down a group (due to increasing electron shells).
  - Ionization Energy: Energy required to remove an electron from an atom. Increases across a period (due to increased nuclear charge) and decreases down a group (due to the outermost electron being farther from the nucleus).
  - Electronegativity: The tendency of an atom to attract electrons in a chemical bond. Increases across a period and decreases down a group.
  - Electron Affinity: The change in energy when an electron is added to a neutral atom. Generally increases across a period and becomes less negative down a group (with exceptions)
Isotopes: Atoms of the same element with different numbers of neutrons.
- Carbon-12 and Carbon-14: Isotopes of carbon used for dating and nuclear chemistry.