IB Chemistry Flashcards: Chemical Bonding
Chemical Bonding Flashcards
20 flashcards covering IB Chemistry chemical bonding — ionic, covalent, metallic bonding, intermolecular forces, VSEPR theory, hybridization, and polarity.
Key Concepts
Ionic Bonding: Transfer of electrons from metal to non-metal, forming cations (+) and anions (−) held by electrostatic attraction. Forms giant ionic lattices with high melting points (strong electrostatic forces), conductivity when molten or dissolved (free-moving ions), and brittle crystalline structure (displacement of layers causes like-charge repulsion). Lattice energy depends on ionic charge and ionic radius (Coulomb’s law). Examples: NaCl (mp 801°C), MgO (mp 2852°C — higher charges and smaller ions give higher lattice energy).
Covalent Bonding: Sharing of electron pairs between non-metals. Single, double, and triple bonds differ in strength and length (triple bonds are strongest and shortest). Coordinate (dative) bonds form when both electrons come from the same atom (e.g., NH₄⁺, CO). Giant covalent structures (diamond, graphite, SiO₂) have very high melting points (strong covalent bonds throughout). Molecular covalent compounds have lower melting points (weak intermolecular forces).
VSEPR Theory: Valence Shell Electron Pair Repulsion theory predicts molecular shape by minimising electron pair repulsion around the central atom. 2 pairs = linear (180°), 3 pairs = trigonal planar (120°), 4 pairs = tetrahedral (109.5°), 5 pairs = trigonal bipyramidal (90°/120°), 6 pairs = octahedral (90°). Lone pairs occupy more space than bonding pairs, compressing bond angles (e.g., NH₃ is 107°, not 109.5°, because the lone pair compresses the three N-H bonds).
Intermolecular Forces: London dispersion forces (present in all molecules, increase with molecular size and number of electrons — temporary dipoles), permanent dipole-dipole forces (polar molecules — permanent partial charges), and hydrogen bonds (H bonded to F, O, or N — the strongest intermolecular force). These determine physical properties like boiling point and solubility. Hydrogen bonding in water explains its unusually high boiling point for its molecular weight.
Intuition
Think of bonding as atoms trying to achieve the stable electron configuration of a noble gas (8 valence electrons, or 2 for hydrogen). Ionic bonding is like one atom giving away a gift (electron) to another — they become attracted because of their new charges. Covalent bonding is like sharing a house — both atoms benefit from the shared electrons. VSEPR is like balloons tied together — they push apart to take up as much space as possible, which determines the molecule’s shape. Intermolecular forces are like magnets between molecules — they’re weak individually but collectively determine whether a substance is a solid, liquid, or gas.
Why it matters: Chemical bonding explains why substances have the properties they do — why salt dissolves in water, why diamond is hard, why oil and water don’t mix, and why DNA maintains its structure. Understanding bonding is essential for predicting chemical behaviour and designing new materials.
Common Pitfalls
- Confusing intermolecular forces with intramolecular (covalent) bonds. Boiling water breaks hydrogen bonds (intermolecular), not O-H covalent bonds. This is why water boils at 100°C, not at thousands of degrees. The boiling point depends on intermolecular forces, not covalent bond strength.
- Assuming all molecules with polar bonds are polar. CO₂ has polar C=O bonds but is linear and symmetrical, so the dipoles cancel. CHCl₃ has polar bonds and is asymmetrical, so it is polar. Shape determines polarity, not just bond polarity.
- Forgetting that London dispersion forces increase with molecular size. This is why I₂ is a solid at room temperature while F₂ is a gas, even though both are non-polar diatomic molecules. More electrons = stronger temporary dipoles.
- Confusing the shape names. Linear = 2 electron domains; trigonal planar = 3; tetrahedral = 4; trigonal bipyramidal = 5; octahedral = 6. The shape depends on the number of electron domains, not just bonding pairs.
Cross-References
- Atomic Structure: Atomic structure determines electron configurations, which determine how atoms bond and what shapes molecules adopt.
- Energetics: Bond energies are used to calculate enthalpy changes — breaking bonds requires energy; forming bonds releases energy.
- Kinetics and Equilibrium: Reaction rates depend on bond strengths, and equilibrium positions are influenced by bond energies.
- Organic Chemistry: Organic chemistry involves specific bonding patterns (C-C, C-H, C=O) and shapes that determine reactivity.
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.