Carbon and its Compounds: The Chemistry of Life

Learning Outcomes
- Explain the unique properties of carbon that lead to diverse compounds
- Describe covalent bonding in carbon compounds with electron dot structures
- Differentiate between saturated and unsaturated hydrocarbons
- Identify and name compounds with common functional groups
- Explain chemical properties like combustion, oxidation, and addition reactions
- Understand the cleaning action of soaps and detergents
Starter Questions
- Why does carbon form so many more compounds than other elements?
- How is the bonding in carbon compounds different from ionic compounds?
- Why do saturated and unsaturated hydrocarbons burn differently?
- What makes ethanol and ethanoic acid important in daily life?
- How do soaps help clean oily dirt from clothes?
Key Concepts & Activities
1. Covalent Bonding in Carbon
Comparison of carbon bonding with other elements:
Element | Valence Electrons | Bonding Method | Example |
---|---|---|---|
Carbon | 4 | Covalent (sharing) | CH4, C2H6 |
Sodium | 1 | Ionic (transfer) | NaCl |
Oxygen | 6 | Covalent (sharing 2) | O2, H2O |
Nitrogen | 5 | Covalent (sharing 3) | N2, NH3 |
Activity 1: Build molecular models of methane, ethene, and ethyne to understand single, double and triple bonds.
2. Hydrocarbons and Functional Groups
Types of hydrocarbons and their properties:
Type | Bonding | General Formula | Example | Flame Test |
---|---|---|---|---|
Alkanes | Single bonds | CnH2n+2 | CH4, C2H6 | Clean blue flame |
Alkenes | Double bond | CnH2n | C2H4, C3H6 | Yellow sooty flame |
Alkynes | Triple bond | CnH2n-2 | C2H2, C3H4 | Very sooty flame |
Activity 2: Test combustion of different hydrocarbons and observe flame characteristics.
3. Important Carbon Compounds
Properties and reactions of ethanol and ethanoic acid:
Compound | Formula | Physical Properties | Key Reactions |
---|---|---|---|
Ethanol | C2H5OH | Colorless liquid, bp 351K, soluble in water | Combustion, oxidation to ethanoic acid, reaction with Na |
Ethanoic acid | CH3COOH | Vinegar smell, bp 391K, freezes at 290K | Esterification, reaction with bases/carbonates |
Activity 3: Perform esterification reaction between ethanol and ethanoic acid.
4. Soaps and Detergents
Comparison of cleaning action:
Aspect | Soap | Detergent |
---|---|---|
Composition | Sodium salt of fatty acids | Synthetic sulphonates |
Action in hard water | Forms scum (insoluble) | Works effectively |
Biodegradability | Highly biodegradable | Some non-biodegradable |
Micelle formation | Yes | Yes |
Activity 4: Compare cleaning action of soap and detergent in hard/soft water.
Period Wise Plan
Total Duration: 8 Periods (45 minutes each)
Period 1: Introduction to Carbon Compounds
Key Topics: Unique properties of carbon, tetravalency, catenation
Activities:
- List carbon compounds used in daily life
- Discuss allotropes of carbon
- Model carbon bonding with molecular kits
Resources: Molecular model kits, samples of carbon allotropes
Period 2: Covalent Bonding
Key Topics: Electron dot structures, single/double/triple bonds
Activities:
- Draw electron dot structures
- Compare properties with ionic compounds
- Build models of H2, O2, N2, CH4
Resources: Chart paper, molecular model kits
Period 3: Hydrocarbons
Key Topics: Alkanes, alkenes, alkynes, structural isomers
Activities:
- Name and draw hydrocarbon structures
- Identify isomers of butane/pentane
- Combustion test comparison
Resources: Hydrocarbon samples, Bunsen burner
Period 4: Functional Groups
Key Topics: Alcohols, aldehydes, ketones, carboxylic acids
Activities:
- Identify functional groups in compounds
- Nomenclature practice
- Test solubility of different groups
Resources: Molecular models, compound samples
Period 5: Chemical Properties
Key Topics: Combustion, oxidation, addition, substitution
Activities:
- Oxidation of ethanol to ethanoic acid
- Hydrogenation of vegetable oil
- Substitution reaction demonstration
Resources: KMnO4, vegetable oil, nickel catalyst
Period 6: Ethanol & Ethanoic Acid
Key Topics: Properties, reactions, uses
Activities:
- Esterification reaction
- Test with sodium carbonate
- Compare pH with mineral acids
Resources: Ethanol, glacial acetic acid, conc. H2SO4
Period 7: Soaps & Detergents
Key Topics: Micelle formation, cleaning action, hard water
Activities:
- Compare soap/detergent in hard water
- Observe micelle formation
- Make simple soap (demonstration)
Resources: Soap solution, detergent, hard water samples
Period 8: Review & Assessment
Key Topics: Concept review, problem solving
Activities:
- Nomenclature quiz
- Reaction prediction exercises
- Practical assessment
Resources: Assessment sheets, molecular models
Teaching Strategies
Assessment Timeline
Formative: Ongoing through periods 1-7 (lab reports, quizzes, models)
Summative: Period 8 (comprehensive test, practical assessment)
Assessment
Formative Assessment
- Observation during molecular model building
- Short quizzes on nomenclature and bonding
- Lab reports on chemical reactions
- Concept maps of hydrocarbon classification
Summative Assessment
- Written exam covering all concepts
- Practical test on identifying functional groups
- Drawing electron dot structures
- Predicting reaction products
Extended Learning
- Research project on allotropes of carbon
- Designing models of complex organic molecules
- Debate on uses of ethanol as fuel
- Investigating biodegradable vs non-biodegradable detergents
Frequently Asked Questions
- Why does carbon form so many compounds?
- Carbon's unique ability to form four covalent bonds (tetravalency) and bond with other carbon atoms (catenation) allows it to form long chains, branched chains, and rings, leading to millions of possible compounds.
- What's the difference between saturated and unsaturated hydrocarbons?
- Saturated hydrocarbons (alkanes) have only single bonds between carbon atoms and are relatively unreactive. Unsaturated hydrocarbons (alkenes and alkynes) contain double or triple bonds and are more reactive.
- Why do unsaturated hydrocarbons burn with a sooty flame?
- The higher carbon content in unsaturated compounds leads to incomplete combustion, producing unburnt carbon particles that appear as soot, unlike saturated hydrocarbons which burn completely with a clean blue flame.
- How does soap clean dirt from clothes?
- Soap molecules form micelles with hydrophobic tails attaching to oil/grease and hydrophilic heads facing water. This emulsifies the dirt, allowing it to be rinsed away with water.
- What's the difference between ethanol and ethanoic acid?
- Ethanol (C2H5OH) is an alcohol - neutral, good solvent. Ethanoic acid (CH3COOH) is a carboxylic acid - sour, acidic. Ethanol can be oxidized to form ethanoic acid.