CHM1022 Week 1 Notes – Introduction to Organic Territory & Alkanes

Unit Overview & Structure

• Unit code: CHM1022 (often referred to verbally as “one-zero-two-two”).
• Central theme: chemistry of organic and inorganic materials – their properties, structures, and inter-conversion.
• Temporal layout
  • Weeks 1–6 ≈ Organic chemistry.
  • Delivered in three 2-week blocks, each by a different organic lecturer.
  • Weeks 7–12 ≈ Inorganic chemistry (metals, coordination, etc.) run by a separate team, also in three 2-week blocks.
• Diverse teaching team; exposure to multiple lecturing styles aims to maximise clarity and engagement.

Lecturer Introduction – Dr David Lupton

• Role this semester: front-load Weeks 1–2 content, appear in several workshops.
• Research focus
  • Discovery of new reactions/strategies for coupling simple molecules into complex, bio-active, sensor-like or aesthetically interesting targets.
  • Example slide: three small feed-stocks → creative reaction design → architecturally elaborate products.
• Personal enthusiasm: 3-D molecular shapes and their “visual intrigue”.

Organic vs Inorganic Territory

• Modified periodic table shown where atom size correlates with natural abundance; H, C, O prominent.
• “Organic zone” = C-centred non-metals (H, C, N, O, P, S, halogens, etc.) – focus of first half.
• “Inorganic zone” = metals and other elements – focus of second half.
• Core study rationale: carbon-containing molecules dominate food, body composition, drugs, fuels, materials.

Everyday Organic Chemistry – Examples & Implications

• Human diet & body composition
  • Foods displayed: sugars, amino-acids/proteins, oleic acid (fatty acid).
  • Human atoms ≈ 98 % O, C, N, H; remaining 2 % essential metals vital for enzymatic function.
• Therapeutics
  • Caffeine (stimulant in coffee), penicillin (classic antibiotic), remdesivir (Pfizer antiviral for COVID, especially immuno-suppressed patients).
• Fuels & Environmental Issues
  • Hydrocarbons propel vehicles; combustion → $\text{CO}_{2}$ buildup.
  • Per-/poly-fluorinated polymers (e.g. Teflon) are chemically inert, confer non-stick surfaces but persist as health & environmental contaminants.
• Materials & Dyes
  • Indigo gives blue-jeans their colour.
  • Cellulose (glucose polymer) furnishes paper; structural similarity to sugars yet vastly different properties.
• Take-home: Organic molecules can be beneficial, harmful or neutral; ubiquity justifies detailed study.

Weekly Workflow & Expectations

1. Pre-week preparation
   • Watch short video clips (like this one).
   • Read corresponding workbook sections.
   • Complete the preparatory quiz before Monday.
2. During the week
   • Attempt worksheet problems in the workbook.
   • Attend workshops: extend clip “skeleton” into detailed, problem-solving sessions.
3. Laboratory component
   • Finish pre-lab exercises by scheduled time.
   • Attend lab, perform experiment, and submit lab report promptly.

Week 1 Learning Objectives (Organic Block 1)

1. Relate carbon hybridisation (sp, sp², sp³) to molecular shape.
2. Recognise & contrast conformational isomers vs alkene stereoisomers (E/Z).
3. Assign E/Z stereochemistry to alkenes.
4. Describe mechanisms, reagents & products for electrophilic addition to alkenes.
5. Predict regio-/stereo-chemical outcomes (handled mainly in subsequent clip).

Drawing Organic Molecules – Levels of Detail

Conventions within skeletal formulae

• Vertex = carbon; missing valences automatically filled with H atoms.
• Dashed bond (___) = bond into page; bold wedge = bond out of page – conveys 3-D stereochemistry.

Functional Groups Illustrated in $C<em>{21}H</em>{30}O_{2}$ Example

• Alcohols – $C–O–H$ unit; ethanol is simplest analogue.
• Ether/ester-like oxygen – O bound to two carbons (specific class not yet emphasised).
• Presence of alkene segment, aromatic (arene) ring, and alkane chains all in one molecule.

Classes of Hydrocarbons

Saturation criterion

• Saturated = maximum H’s; only single bonds (alkanes).
• Unsaturated = contains π bonds or rings reducing H count (alkenes, alkynes, arenes).

Family summary

1. Alkanes – C–C single (σ) bonds; general formula $C<em>{n}H</em>{2n+2}$.
   • Example ethane: $CH<em>{3}–CH</em>{3}$.
2. Alkenes – C=C double bonds; at least one π bond.
   • Example ethene: $CH<em>{2}=CH</em>{2}$.
3. Alkynes – C≡C triple bonds.
   • Example ethyne (acetylene): $CH\equiv CH$.
4. Arenes (aromatic rings) – cyclic system with alternating single-/double-bond pattern (benzene major prototype).

Course roadmap

• Today: Alkanes.
• Next clip: Alkenes (structure, stereochemistry, reactions).
• Week 2: Arenes.

Alkanes – Structure & Bonding

• Carbon is sp³ hybridised → four equivalent $\sigma$ bonds in a tetrahedral (≈109.5°) geometry.
• Visualised via orbital overlap animation: two sp³ orbitals (each with one e⁻) combine → σ C–C bond.
• Molecular formula check: if a hydrocarbon obeys $C<em>{n}H</em>{2n+2}$ (e.g. $C<em>{2}H</em>{6}$ where $n=2$) and has no rings/π bonds, it is an alkane.
• Chemical reactivity: generally low – primary use is combustion for energy; chemical functionalisation requires specific, often harsh conditions.

Molecular Motion & Conformational Analysis

• All molecules are dynamic: rotate about single bonds, twist, vibrate.
• Conformation = particular 3-D arrangement at an instant.
• Even simple ethane possesses an energy surface of conformers that interconvert rapidly at room temperature.
• Large pharmaceuticals exploit flexibility to fit biological targets (example: Linezolid bound deep within ribosome cavity; cryo-EM structure from Monash University showed folded ring orientation bringing an oxygen into optimal contact).

Newman & Sawhorse Projections – Visualising Conformations

1. Newman projection (sight-down a specific C–C bond)
   • Front carbon shown as dot; back carbon as circle.
   • Example (ethane, staggered): front H’s at 120°; rear H’s offset 60° → minimal torsional strain.
   • Staggered vs eclipsed (0° offset) conformers differ in energy.
2. Sawhorse projection (oblique side view)
   • Front carbon drawn lower-left, back carbon upper-right (or vice versa).
   • Bonds drawn as straight lines of appropriate angles; conveys same torsional information but with depth perspective.

Hybridisation Refresher

• Detailed recap video uploaded separately for those needing reinforcement (originally covered in CHM1011).

Key Numerical & Symbolic Facts to Memorise

• Human atom %: O ≈ 65 %, C ≈ 18 %, H ≈ 10 %, N ≈ 3 % → ≈ 98 % together; metals ≈ 2 % but essential.
• Alkane formula: $C<em>{n}H</em>{2n+2}$; Alkene if H count < $2n+2$ by 2 per π bond or by 2 per ring.
• Tetrahedral angle ≈ $109.5^{\circ}$ (often simplified to $109^{\circ}$ in lecture slides).

Ethical, Environmental & Practical Implications Discussed

• Pharmaceutical development (e.g. remdesivir) demonstrates life-saving side of organic chemistry.
• Hydrocarbon fuels tied to global CO₂ emissions; chemical literacy needed for sustainable transition.
• Fluorinated polymers: convenience vs long-term ecological/health costs (persistent organic pollutants).

Final Take-Home Messages

• Organic chemistry underpins food, health, energy, and materials – ubiquitous, consequential, worthy of in-depth study.
• Mastery of drawing conventions and hybridisation concepts is foundational; they unlock understanding of shape, reactivity, and properties.
• Alkanes provide the flexible, low-reactivity skeleton; forthcoming lectures will append functional/reactive features (alkenes, arenes, stereochemistry, reactions).