IB Chemistry Flashcards: Atomic Structure
Atomic Structure Flashcards
20 flashcards covering IB Chemistry atomic structure — atomic models, subatomic particles, isotopes, mass spectrometry, electron configurations, and periodic trends.
Key Concepts
Subatomic Particles: Protons (positive charge, relative mass ~1, defines the element — atomic number Z), neutrons (no charge, relative mass ~1, determines the isotope), and electrons (negative charge, relative mass ~1/1836, determines chemical behaviour). The number of protons defines the element (atomic number Z). Isotopes have the same Z but different numbers of neutrons (different mass numbers). Ions form when atoms gain or lose electrons (anions gain electrons; cations lose electrons).
Mass Spectrometry separates ions by their mass-to-charge ratio (m/z). The molecular ion peak (M⁺) gives the molecular mass. The base peak is the tallest (most abundant) peak — it represents the most stable ion. Isotopic peaks (M+1, M+2) reveal the presence of isotopes like ¹³C (1.1% natural abundance) and ³⁷Cl (25% natural abundance). The M+2 peak pattern helps identify elements: Cl shows a 3:1 ratio (M:M+2); Br shows a 1:1 ratio.
Electron Configuration: Electrons fill orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p… Each orbital holds a maximum of 2 electrons with opposite spins (Pauli exclusion principle). The aufbau principle (fill lowest energy first), Pauli exclusion principle (max 2 electrons per orbital, opposite spins), and Hund’s rule (fill degenerate orbitals singly first, with parallel spins) govern filling. Full electron configurations and abbreviated noble gas configurations are both required.
Ionisation Energy: The energy required to remove one mole of electrons from one mole of gaseous atoms. First ionisation energy generally increases across a period (more protons, smaller radius, stronger nuclear attraction) and decreases down a group (more shielding, larger radius, weaker nuclear attraction). Exceptions occur at Groups 2/13 (2p vs 2p — removing from a higher energy subshell is easier) and 15/16 (paired p electrons repel, making removal easier).
Intuition
Think of an atom as a solar system where electrons occupy specific “orbitals” (rooms in a building) rather than random orbits. The aufbau principle is like filling the building from the ground up — you can’t put someone on the 3rd floor if the 1st floor isn’t full yet. Ionisation energy is the rent you must pay to evict an electron — closer electrons (lower energy levels) are harder to evict because they’re more tightly held by the nucleus. Mass spectrometry is like weighing individual atoms — it reveals their mass and abundance.
Why it matters: Atomic structure is the foundation of all chemistry. Understanding electron configurations explains chemical bonding, reactivity, and periodic trends. Mass spectrometry is essential for identifying unknown compounds and determining molecular formulas.
Common Pitfalls
- Forgetting that the 4s orbital fills before the 3d orbital. The energy ordering is 1s < 2s < 2p < 3s < 3p < 4s < 3d, not directly by principal quantum number. This is a common exam error in electron configuration questions.
- Confusing ionisation energy trends. It generally increases across a period, but there are dips at Groups 2→13 (s vs p subshell) and 15→16 (paired p electrons repel). These exceptions are frequently tested and must be explained in terms of subshell energy and electron-electron repulsion.
- Misreading mass spectra. The molecular ion peak (M⁺) is not always the base peak. Always identify M⁺ first, then use the relative heights of M+1 and M+2 peaks to determine molecular formula. The M+2 pattern reveals the presence of Cl or Br.
- Forgetting that ionisation energy is measured for gaseous atoms. This removes intermolecular forces from the measurement, giving a pure measure of nuclear-electron attraction.
Cross-References
- Chemical Bonding: Chemical bonding depends on electron configurations — how atoms gain, lose, or share electrons to achieve stable configurations.
- Energetics: Energy changes in reactions are related to ionisation energy, electron affinity, and bond energies — all connected to atomic structure.
- Periodicity: Periodic trends (atomic radius, ionisation energy, electronegativity) are explained by atomic structure and electron configuration.
- Stoichiometry: Stoichiometry uses the mole concept, which relates to the number of atoms and their masses.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.