IB Chemistry Flashcards: Periodicity
IB Chemistry — Periodicity Flashcards
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Key Concepts
Period 3 Trends: Across Period 3 (Na to Ar), atomic radius decreases (more protons pull electrons closer), ionisation energy increases (stronger nuclear attraction), and electronegativity increases (greater ability to attract bonding electrons). The metallic character decreases (Na is a reactive metal, Mg is less reactive, Al is amphoteric, Si is a metalloid, P/S/Cl/Ar are non-metals). Oxide acidity increases across the period: Na₂O and MgO are basic; Al₂O₃ is amphoteric (reacts with both acids and bases); SiO₂, P₄O₁₀, SO₃, and Cl₂O₇ are acidic.
Group 1 (Alkali Metals): Reactivity increases down the group as ionisation energy decreases (outer electron is further from nucleus and more shielded by inner shells). They react vigorously with water to form hydroxides and hydrogen gas (2Na + 2H₂O → 2NaOH + H₂). Flame colours: Li = red, Na = yellow, K = lilac, Rb = red-violet, Cs = blue-violet. Stored in oil (less dense than water, react with air and moisture). Melting points decrease down the group.
Group 17 (Halogens): Reactivity decreases down the group as electronegativity decreases and atomic radius increases. They are diatomic molecules (F₂, Cl₂, Br₂, I₂). Displacement reactions: more reactive halogens displace less reactive ones from their salts (e.g., Cl₂ + 2NaBr → 2NaCl + Br₂). Colour deepens down the group: F₂ (pale yellow gas), Cl₂ (green-yellow gas), Br₂ (red-brown liquid), I₂ (purple-black solid). Hydrogen halides dissolve in water to form acids (HF weak, HCl/HBr/HI strong).
Transition Metals: Characteristic properties include variable oxidation states (e.g., Fe²⁺ and Fe³⁺), coloured compounds (Cu²⁺ blue, Fe³⁺ yellow, Ni²⁺ green), catalytic activity (MnO₂ in H₂O₂ decomposition), and complex ion formation (Cu(NH₃)₄²⁺ deep blue). They form ions with incomplete d-subshells. Iron, copper, and zinc are the most commonly studied. Transition metals are harder and denser than Group 1 metals.
Intuition
Think of the periodic table as a city map. Moving left to right across a period is like walking down a single street — properties change gradually as you pass each building (element). Moving down a group is like looking at the same building in different cities — the basic structure is similar, but things get bigger and more spread out. Group 1 metals are like eager volunteers (reactive, willing to give away electrons), while Group 17 halogens are like aggressive collectors (reactive, wanting to take electrons). Transition metals are versatile workers with multiple skills (variable oxidation states).
Why it matters: Periodicity explains why elements behave the way they do and predicts chemical behaviour of unfamiliar elements. It’s the foundation of inorganic chemistry and is essential for understanding bonding, reactivity, and material properties.
Common Pitfalls
- Assuming all Group 1 metals react the same way. They do react similarly, but reactivity increases dramatically down the group — lithium reacts gently with water while potassium reacts violently and can ignite the hydrogen produced. The trend matters, not just the general behaviour.
- Confusing ionisation energy trends across and down the period table. Across a period: increases (more protons, smaller radius, stronger attraction). Down a group: decreases (more shielding, larger radius, weaker attraction). These trends have opposite directions.
- Forgetting that transition metals have variable oxidation states. Iron can be Fe²⁺ or Fe³⁺; copper can be Cu⁺ or Cu²⁺. The oxidation state determines the compound’s formula and properties. Always specify the oxidation state in formulas.
- Confusing metallic character with reactivity. Sodium is more metallic than magnesium (further left in the period), but magnesium is less reactive with water. Reactivity depends on specific reactions, not just metallic character.
Cross-References
- Atomic Structure: Atomic structure (electron configuration, atomic radius) explains periodic trends in ionisation energy and electronegativity.
- Chemical Bonding: Bonding types (ionic, covalent, metallic) are determined by position in the periodic table and explain physical properties.
- Energetics: Lattice energies, ionisation energies, and electron affinities are periodic properties that determine compound stability.
- Stoichiometry: Stoichiometric calculations use molar masses, which are determined by atomic structure.
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.