Podcast
Questions and Answers
What is the bond angle in a trigonal planar molecule?
What is the bond angle in a trigonal planar molecule?
- 90°
- 109.5°
- 180°
- 120° (correct)
Which statement is true regarding pi bonds?
Which statement is true regarding pi bonds?
- They have less overlap compared to sigma bonds. (correct)
- They contribute to the geometry of a tetrahedral molecule.
- They only occur between two p orbitals.
- They can exist independently of sigma bonds.
Which molecule has a tetrahedral shape?
Which molecule has a tetrahedral shape?
- CH4 (correct)
- CO2
- BF3
- NH3
How many pairs of electrons are present in a linear molecule?
How many pairs of electrons are present in a linear molecule?
Which molecular shape corresponds to 3 bonded pairs and 1 lone pair of electrons?
Which molecular shape corresponds to 3 bonded pairs and 1 lone pair of electrons?
Which of the following elements can expand its octet by utilizing the d-subshell?
Which of the following elements can expand its octet by utilizing the d-subshell?
According to VSEPR theory, what influences the shape of a molecule?
According to VSEPR theory, what influences the shape of a molecule?
What is the primary factor in determining bond angles in a molecule?
What is the primary factor in determining bond angles in a molecule?
What type of forces are present between noble gases like helium and neon?
What type of forces are present between noble gases like helium and neon?
Which statement best describes how Van der Waals forces behave?
Which statement best describes how Van der Waals forces behave?
Under what conditions do gases tend to behave ideally?
Under what conditions do gases tend to behave ideally?
What aspect do real gases deviate from in the kinetic theory of gases?
What aspect do real gases deviate from in the kinetic theory of gases?
What is the relationship between temperature and the average kinetic energy of gas molecules?
What is the relationship between temperature and the average kinetic energy of gas molecules?
How do induced dipoles form in non-polar molecules?
How do induced dipoles form in non-polar molecules?
Why is the volume of gas considered negligible?
Why is the volume of gas considered negligible?
What happens during elastic collisions between gas particles?
What happens during elastic collisions between gas particles?
What is the structure formed by water molecules in ice due to hydrogen bonding?
What is the structure formed by water molecules in ice due to hydrogen bonding?
What type of forces hold Buckminsterfullerenes (C60) together?
What type of forces hold Buckminsterfullerenes (C60) together?
Why is ice less dense than liquid water?
Why is ice less dense than liquid water?
Which property of fullerene (C60) allows it to conduct heat and electricity?
Which property of fullerene (C60) allows it to conduct heat and electricity?
How many hydrogen bonds does each water molecule form in ice?
How many hydrogen bonds does each water molecule form in ice?
Which characteristic correctly describes the solubility of fullerenes in water?
Which characteristic correctly describes the solubility of fullerenes in water?
What type of molecular interaction is primarily responsible for the diatomic molecules formed by covalent bonds?
What type of molecular interaction is primarily responsible for the diatomic molecules formed by covalent bonds?
What is the molecular arrangement of carbon atoms in Buckminsterfullerenes?
What is the molecular arrangement of carbon atoms in Buckminsterfullerenes?
What is the process of breaking down a molecule using water, often sped up by an acid or alkali?
What is the process of breaking down a molecule using water, often sped up by an acid or alkali?
Which type of bond fission involves the equal sharing of electrons between two atoms, resulting in the formation of free radicals?
Which type of bond fission involves the equal sharing of electrons between two atoms, resulting in the formation of free radicals?
What characterizes a free radical?
What characterizes a free radical?
Which of the following best describes the shape and bond angles of ethene?
Which of the following best describes the shape and bond angles of ethene?
What occurs to the boiling point of straight-chain alkanes compared to branched alkanes?
What occurs to the boiling point of straight-chain alkanes compared to branched alkanes?
In terms of oxidation and reduction, which statement is correct?
In terms of oxidation and reduction, which statement is correct?
Which statement regarding isomers is true?
Which statement regarding isomers is true?
What type of bonds are present in ethane?
What type of bonds are present in ethane?
What can we conclude when the value of Kc is smaller?
What can we conclude when the value of Kc is smaller?
Which of these factors can affect the value of Kp?
Which of these factors can affect the value of Kp?
What does the value of the equilibrium constant (K) tell us about a reaction?
What does the value of the equilibrium constant (K) tell us about a reaction?
What is the correct expression for Kc for the following reaction: $2NO_2(g)⇌N_2O_4(g)$?
What is the correct expression for Kc for the following reaction: $2NO_2(g)⇌N_2O_4(g)$?
What is the difference between Kc and Kp?
What is the difference between Kc and Kp?
Which of the following statements about the Brønsted–Lowry theory of acids and bases is true?
Which of the following statements about the Brønsted–Lowry theory of acids and bases is true?
In a chemical reaction, where the forward reaction is exothermic, what is the effect of increasing the temperature on the equilibrium constant (K) ?
In a chemical reaction, where the forward reaction is exothermic, what is the effect of increasing the temperature on the equilibrium constant (K) ?
What is the molar ratio of reactants to products for the following balanced equation: $N_2(g) + 3H_2(g) ⇌ 2NH_3(g)$?
What is the molar ratio of reactants to products for the following balanced equation: $N_2(g) + 3H_2(g) ⇌ 2NH_3(g)$?
Which halogen is most likely to react with concentrated sulfuric acid to produce a hydrogen halide, sulfur dioxide, and water?
Which halogen is most likely to react with concentrated sulfuric acid to produce a hydrogen halide, sulfur dioxide, and water?
Which of these halogen is the least volatile?
Which of these halogen is the least volatile?
What is the general trend in the oxidising ability of halogens down the group?
What is the general trend in the oxidising ability of halogens down the group?
Why is concentrated sulfuric acid a good choice for preparing hydrogen halides in these reactions?
Why is concentrated sulfuric acid a good choice for preparing hydrogen halides in these reactions?
Which of the following describes the complex ion [H3N:⟶Ag←:NH3]+?
Which of the following describes the complex ion [H3N:⟶Ag←:NH3]+?
Which of the following halogens is a gas at room temperature?
Which of the following halogens is a gas at room temperature?
Which element will react with concentrated sulfuric acid to produce hydrogen bromide?
Which element will react with concentrated sulfuric acid to produce hydrogen bromide?
Looking at the colour trends of the halogens down the group, what observation can be made?
Looking at the colour trends of the halogens down the group, what observation can be made?
Flashcards
Noble Gases
Noble Gases
Helium and neon with low intermolecular forces, approaching ideal behavior.
Intermolecular Forces
Intermolecular Forces
Weak forces between molecules, including induced dipoles and permanent dipoles.
Induced Dipole
Induced Dipole
Temporary dipole in a non-polar molecule due to electron density distortion.
Van der Waals Forces
Van der Waals Forces
Weak forces that arise between non-polar molecules, increasing with contact points.
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Ideal Gas Laws
Ideal Gas Laws
Rules describing how ideal gases behave under high temperature and low pressure.
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Kinetic Theory Limitations
Kinetic Theory Limitations
Real gases deviate from ideal behavior due to attractions and molecular volume.
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Permanent Dipole-Dipole Forces
Permanent Dipole-Dipole Forces
Attractive forces between polar molecules due to their permanent dipoles.
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Ideal Gas Behavior Conditions
Ideal Gas Behavior Conditions
Occurs at high temperatures and low pressures for gases to behave ideally.
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Dative Covalent Bond
Dative Covalent Bond
A bond formed when one atom donates both electrons to a bond.
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Sigma Bond (σ)
Sigma Bond (σ)
A type of bond with greater overlap allowing for strong electron sharing.
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Pi Bond (π)
Pi Bond (π)
A bond that exists only when a sigma bond is present.
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Trigonal Planar
Trigonal Planar
Shape formed when there are 3 bonded pairs of electrons and no lone pairs.
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Tetrahedral
Tetrahedral
Shape of molecules with 4 bonded pairs and no lone pairs of electrons.
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VSEPR Theory
VSEPR Theory
Theory that states electron pairs arrange to minimize repulsion.
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Pyramidal Shape
Pyramidal Shape
Shape with 3 bonded pairs and 1 lone pair of electrons.
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Linear Shape
Linear Shape
Shape formed when there are 2 bonded pairs and no lone pairs.
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Diamine Silver(I) Ion
Diamine Silver(I) Ion
A complex ion formed with silver and two amine ligands.
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Halogen Colors
Halogen Colors
The colors of halogens vary from yellow for fluorine to black for astatine.
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Volatility Trend in Halogens
Volatility Trend in Halogens
Volatility decreases down the group of halogens from fluorine to iodine.
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Oxidising Ability of Halogens
Oxidising Ability of Halogens
Halogens are strong oxidising agents due to high electron affinity, decreasing down the group.
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Reactions with Sulfuric Acid
Reactions with Sulfuric Acid
Halides react with concentrated sulfuric acid to form hydrogen halides.
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Electron Affinity Trend
Electron Affinity Trend
Electron affinity decreases down the halogen group as atomic size increases.
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Colors of Halogen States
Colors of Halogen States
The physical state colors of halogens: yellow gas (Cl), orange liquid (Br), black solid (I).
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Hydrogen Halide Formation
Hydrogen Halide Formation
The process of forming hydrogen halides from metal halides and sulfuric acid.
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Diatomic Molecules
Diatomic Molecules
Molecules consisting of two atoms formed by covalent bonds.
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Weak Van der Waals Forces
Weak Van der Waals Forces
Attractive forces between molecules that are relatively weak.
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Hydrogen Bonds in Ice
Hydrogen Bonds in Ice
Strong intermolecular forces between water molecules forming a lattice in ice.
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Crystalline Structure of Ice
Crystalline Structure of Ice
Ice has an open hexagonal structure due to hydrogen bonding.
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Density of Ice
Density of Ice
Ice is less dense than water due to its crystalline structure.
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Fullerenes
Fullerenes
Molecules composed of carbon arranged in pentagonal and hexagonal shapes, like C60.
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Conductivity of Fullerenes
Conductivity of Fullerenes
Fullerenes can conduct heat and electricity due to their structure.
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Insolubility in Water
Insolubility in Water
Fullerenes do not dissolve in water, maintaining their structure.
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Equilibrium Constant (Kc)
Equilibrium Constant (Kc)
A ratio of product concentrations to reactant concentrations at equilibrium, excluding solids.
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Equilibrium Constant (Kp)
Equilibrium Constant (Kp)
A ratio of partial pressures of products to reactants at equilibrium; used only for gases.
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Large Kc/Kp Value
Large Kc/Kp Value
Indicates that the equilibrium favors the formation of products.
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Small Kc/Kp Value
Small Kc/Kp Value
Indicates that the equilibrium favors the formation of reactants.
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Temperature Effect on Kc/Kp
Temperature Effect on Kc/Kp
The value of Kc or Kp changes only with temperature changes, not concentration or pressure.
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Balanced Equation Ratios
Balanced Equation Ratios
The ratios of reactants disappearing match the ratios of products forming, according to the balanced equation.
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Only gases and liquids in equilibrium
Only gases and liquids in equilibrium
Kc and Kp only include gases and liquids, not solids in the equilibrium expression.
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Equilibrium Expression
Equilibrium Expression
A mathematical expression that relates the concentrations or pressures of the products and reactants at equilibrium.
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Hydrolysis Reaction
Hydrolysis Reaction
Breaking down a molecule using water, often accelerated by acid or alkali.
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Homolytic Fission
Homolytic Fission
Bond breaking where each atom takes one electron, creating free radicals.
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Free Radicals
Free Radicals
Atoms or groups with unpaired electrons, very reactive due to their instability.
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Heterolytic Fission
Heterolytic Fission
Bond breaking where one atom takes both electrons, leading to ions.
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Oxidation
Oxidation
Chemical reaction involving the addition of oxygen or removal of hydrogen.
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Reduction
Reduction
Chemical reaction involving the addition of hydrogen or removal of oxygen.
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Ethane Shape
Ethane Shape
Ethane has sp3 bonds and is characterized by all sigma bonds.
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Ethene Shape
Ethene Shape
Ethene has a planar shape with H-C-H bond angles of 120 degrees.
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CAIE AS Level Chemistry Summary Notes
- Updated to 2023-2025 syllabus
- Summarized notes on the theory syllabus
1. Atoms, Molecules, and Stoichiometry
- 1.1. Relative Mass
- Atomic mass (Ar): weighted average mass of an atom
- Molecular mass (Mr): mass of a molecule
- Formula mass: mass of one formula unit of a compound
- Isotopic mass: mass of a particular isotope of an element
- Unified atomic mass unit: u = 1.66 x 10⁻²⁷ kg
- 1.2. The Mole
- Mole: amount of substance with the same number of particles as 12g of carbon-12 isotope
- Avogadro's constant: number of particles in a mole (6.02 × 10²³)
- 1.3. Mass Spectra
- Abundance of isotopes can be visualized on a mass spectra diagram
- Relative Abundance = (Peak Height / Total Height) x 100%
- 1.4. Empirical and Molecular Formulae
- Empirical Formula: simplest whole number ratio of atoms in a compound
- Molecular Formula: actual number of atoms of each element in a molecule
- Molecular Formula = (Empirical Formula)n where n = (Molecular Mass/Mass of Empirical Formula)
- % Composition: percentage of each element within the compound
2. Chemical Bonding
- 2.1. Electronegativity and Bonding
- Electronegativity: power of an atom to attract electrons
- Increases across periods, decreases down groups
- Dipole Moment: slight charges on atoms in a bond due to differences in electronegativity
- 2.2. Ionic (Electrovalent) Bonding
- Electrostatic attraction between oppositely charged ions (ions)
- Structure: giant ionic lattice / crystalline solids; High m.p./b.p.
- Coordination Number: number of ions surrounding a given ion in an ionic solid
- 2.3. Dot and Cross Diagrams
- 2.4. Metallic Bonding
- Strong electrostatic forces of attraction between metal cations and delocalized mobile electrons
- Structure: lattice of +ve ions surrounded by mobile electrons
- 2.5. Covalent Bonding
- Sharing of electron pairs between nuclei of two atoms.
- Bonding electrons: electrons involved in bond formation
- Non-bonding electrons: electron pairs not involved in bonding (lone pairs).
- 2.6. Coordinate (Dative Covalent) Bonding
- Both electrons in the bond come from the same atom
- 2.7. Orbital Overlap
- Atomic orbitals containing unpaired valence electrons need to overlap to form a covalent bond.
- 2.8. Shapes of Molecules
- Molecular shape determined by electron pairs surrounding central atom (lone pairs and bonded).
- VSEPR Theory used to determine the molecular geometry and bond angles.
- VSEPR (valence shell electron pair repulsion) Theory used to describe the 3D shape of molecules.
3. States of Matter
- 3.1. Basic Assumptions of Kinetic Theory
- Real gases deviate from ideal behaviour at high pressure and low temperature as volume of molecules become considerable and intermolecular forces attract each other significantly.
- Idea gases have rapidly moving and randomly moving particles. The distance between gases is greater than the size of molecules. Forces of attraction do not exist between the molecules. No forces of attraction/repulsion between molecules.
4. Chemical Energetics
- 4.1. Energy Change In Reactions
- Exothermic reactions: release energy (heat)
- Surroundings get warmer
- Bond making.
- ΔH (enthalpy change) negative
- Endothermic reactions: absorb energy (heat)
- Surroundings get colder
- Bond breaking
- ΔH positive
- 4.2. Reaction Pathway Diagrams
- 4.3. Activation Energy
- 4.4. Enthalpy Change Definitions
5. Equilibria
- 5.1. Introduction
- Reversible reaction: can proceed forward and backward.
- Dynamic Equilibrium: forward and backward reactions occur at equal rates.
6. The Periodic Table: Chemical Periodicity
7. Group 2
8. Group 17
9. Nitrogen and Sulfur
10. An Introduction to AS Level Organic Chemistry
11. Hydrocarbons
12. Halogen Compounds
13. Hydroxy Compounds
14. Carbonyl Compounds
15. Carboxylic Acids and Derivatives
16. Nitrogen Compounds
17. Polymerisation
18. Organic Synthesis
19. Analytical Techniques
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