China 高三 Chemistry

1. Selective 3 Ch.1 Organic structure and methods

Bonding, isomerism, functional groups · Separation, purification, structure determination

• IUPAC Nomenclature and Isomerism of Organic Compounds – Millions of organic compounds exist, so every one needs a clear, unique name. The IUPAC system builds a name from three parts: the word root (number of carbons in the main chain), the suffix (type of bond and main functional group) and the prefixes (side groups). You pick the longest chain that holds the main group, number it so the main group and branches get the lowest numbers, and write side groups in alphabetical order. Isomers are compounds with the same molecular formula but different arrangement. Structural isomers differ in how atoms are joined (chain, position, functional group, metamerism). Stereoisomers are joined the same way but differ in 3D arrangement (geometrical cis/trans and optical isomers).
• Purification and Analysis of Organic Compounds – A compound made in a lab or taken from a plant is never pure at first. We purify it by using a difference in properties: solubility (crystallisation), boiling point (distillation and its types), sublimation, solubility in two liquids (differential extraction) or how strongly it sticks to a surface (chromatography). A pure solid has a sharp melting point. Next we find which elements are present (qualitative analysis): carbon and hydrogen by heating with copper(II) oxide, and N, S, halogens and P by Lassaigne's sodium fusion test. Finally we find how much of each element is present (quantitative analysis): Liebig's method for C and H, Dumas and Kjeldahl methods for N, Carius method for halogens and S, and oxygen by difference. From the percentages we can get the empirical formula.

2. Selective 3 Ch.2 Hydrocarbons

Alkanes · Alkenes and alkynes · Aromatic hydrocarbons

• Alkanes – Alkanes are hydrocarbons with only single C–C bonds. Their general formula is CnH2n+2. We make them by adding hydrogen to alkenes, by the Wurtz reaction, by reducing alkyl halides and by decarboxylation. They are non-polar, burn with a lot of heat and swap H for Cl in light. Around the C–C bond the molecule can twist into staggered and eclipsed shapes called conformations.
• Alkenes – Alkenes are hydrocarbons with one C=C double bond and the formula CnH2n. The double bond is one σ bond plus one π bond, so the molecule is flat around it and cannot twist. That gives cis and trans isomers. We make alkenes by removing small molecules (H₂O, HX, X₂) or by partly adding H₂ to alkynes. Alkenes mainly do addition reactions: H₂, X₂, HX (Markovnikov rule, or anti-Markovnikov with peroxide), water, ozone, KMnO₄ and polymerisation.
• Benzene and Aromaticity – Benzene (C₆H₆) is a flat ring of six sp² carbons. Its six π electrons are spread over the whole ring, so all C–C bonds are equal and the ring is extra stable. A ring like this is called aromatic when it is cyclic, planar, fully conjugated and has 4n + 2 π electrons (Hückel rule). Benzene prefers electrophilic substitution (nitration, halogenation, sulphonation, Friedel–Crafts) over addition, because substitution keeps the stable ring. A group already on the ring decides where the next group goes: ortho/para or meta. Benzene and fused-ring hydrocarbons are toxic and can cause cancer.

3. Selective 3 Ch.3 Hydrocarbon derivatives

Haloalkanes · Alcohols and phenols · Aldehydes and ketones · Carboxylic acids and derivatives · Organic synthesis

• Haloalkanes – A haloalkane is an alkane in which a hydrogen is replaced by a halogen (R–X). The C–X bond is polar: carbon is slightly positive, so nucleophiles attack it. Haloalkanes react by SN2 (one step, backside attack, inversion; best for 1°), SN1 (two steps, flat carbocation, racemic product; best for 3°) or elimination (strong base in alcohol gives an alkene).
• Alcohols – An alcohol is a carbon compound with an –OH group on an sp³ carbon (R–OH). Count the carbons joined to the C–OH carbon to classify it as primary (1°), secondary (2°) or tertiary (3°). Name it as alkan-n-ol, giving –OH the lowest number. Make alcohols from alkenes (acid-catalysed hydration or hydroboration–oxidation), by reducing aldehydes, ketones and acids, or from Grignard reagents. H-bonding gives them high boiling points and water solubility. Reactions break either the O–H bond (acidic: Na, esterification) or the C–O bond (HX, dehydration), and 1°/2° alcohols can be oxidised. Methanol and ethanol are the key commercial alcohols.
• Aldehydes and Ketones: Structure, Preparation and Reactions – Aldehydes and ketones both have a carbonyl group, C=O. In an aldehyde the carbonyl carbon has at least one H on it (−CHO). In a ketone it has two carbon groups (−CO−). The C=O bond is polar: carbon is slightly positive, oxygen slightly negative. So electron-rich particles (nucleophiles) attack the carbon. This one idea explains most of their reactions: addition of HCN, NaHSO₃, alcohols and ammonia derivatives. Aldehydes are easy to oxidise (Tollens and Fehling tests), ketones are not. A hydrogen on the carbon next to C=O (α-H) is slightly acidic, which gives aldol condensation. Aldehydes with no α-H give the Cannizzaro reaction instead.
• Carboxylic Acids: Carboxyl Group, Acidity and Reactions – A carboxylic acid has the carboxyl group, −COOH: a C=O and an O−H on the same carbon. It can give away H⁺, and the ion left behind (carboxylate, −COO⁻) is stable because its negative charge is shared equally by two oxygen atoms. That is why these acids are stronger than phenols and alcohols (but weaker than mineral acids like HCl). Groups that pull electrons (Cl, F, NO₂) make the acid stronger; groups that push electrons (alkyl) make it weaker. We make carboxylic acids by oxidising alcohols, aldehydes or alkylbenzenes, by hydrolysing nitriles, esters and amides, or from Grignard reagents and CO₂. Their key reactions: salt formation with NaHCO₃ (CO₂ fizz), esterification, acid chloride and anhydride formation, reduction to alcohols, decarboxylation and the HVZ reaction.
• Organic Synthesis – Organic synthesis means making a target molecule from simpler starting materials through a planned series of reactions. Each step changes one functional group and needs the right reagent and conditions (temperature, catalyst, solvent, reflux or distillation). Families of compounds are linked (alkane ↔ alkene → haloalkane → alcohol → aldehyde/ketone → carboxylic acid → ester; haloalkane → amine or nitrile), so we can move between them like stations on a map. Chemists plan backwards from the target (retrosynthesis), prefer short routes with high yield and atom economy, and then carry out the reaction, separate, purify and check the product.

4. Selective 3 Ch.4 Biological macromolecules

Sugars · Proteins · Nucleic acids

• Carbohydrates: Classification, Glucose, Disaccharides and Polysaccharides – Carbohydrates are sugars and the big molecules made from sugars. Chemically they are polyhydroxy aldehydes or ketones (many –OH groups plus one C=O), or things that give these on hydrolysis. We sort them by how many sugar units they have: one (monosaccharide), two to ten (oligosaccharide) or many (polysaccharide). Glucose is an aldose with six carbons; fructose is a ketose. Two units join by a glycosidic (–O–) bond to give disaccharides like sucrose, maltose and lactose. Hundreds join to give starch, cellulose and glycogen.
• Proteins and Enzymes: Amino Acids, Peptide Bond, Structure and Denaturation – Proteins are long chains of amino acids. Each amino acid has an amino group (–NH₂), an acid group (–COOH), a hydrogen and a side group R on one carbon. The –COOH of one amino acid joins the –NH₂ of the next, losing water, to make a peptide bond (–CO–NH–). The order of amino acids is the primary structure; coils and sheets are the secondary structure; the full 3D fold is the tertiary structure; several chains together make the quaternary structure. Heat, acid or alcohol can undo the folds (denaturation). Enzymes are mostly proteins that speed up reactions in the body.
• Vitamins, Nucleic Acids and Hormones: Types, Roles, DNA and RNA – Vitamins are small organic compounds we need in tiny amounts from food; A, D, E, K dissolve in fat and B, C dissolve in water, and a lack of each causes a known disease. Nucleic acids (DNA and RNA) are long chains of nucleotides. Each nucleotide = a pentose sugar + a phosphate + a nitrogen base. DNA has deoxyribose, bases A, G, C, T and two strands in a double helix, where A pairs with T and G with C. RNA has ribose, U instead of T and usually one strand. Hormones are chemical messengers made by glands, and can be steroids, proteins/peptides or amino acid derivatives.

5. Selective 3 Ch.5 Synthetic polymers

Addition and condensation polymerisation · Polymer materials

• Polymers – A polymer is a giant molecule made by joining many small molecules (monomers) into a long chain. In addition polymerisation, monomers with a C=C double bond open up and link with nothing lost (ethene → poly(ethene)). In condensation polymerisation, two kinds of monomer with reactive groups at both ends join and give off a small molecule such as water at every link (nylon, polyester). Nature makes polymers too: starch, cellulose, proteins, DNA, rubber. Separate chains give thermoplastics that melt and can be recycled; cross-linked chains give thermosets that never melt. Most plastics do not rot, so we must reduce, reuse and recycle them.

6. Elective series 1: Experimental chemistry

Basic experiments; principle inquiries; industrial-process simulation; STSE experiments

• Chemistry Experiments: Prepare, Separate, Test and Measure – Four skills run through every chemistry lab: prepare a substance, separate it from a mixture, test to identify it, and measure exact amounts (as in titration). The same ideas scale up to a factory model with recycling, and to testing water for pH and nitrate.

7. Elective series 2: Chemistry and society

Chemistry and life; chemistry and technology; STSE practice

• Chemistry in Health, Materials, Industry and Society – Chemistry explains the energy in food, why drug dose matters, why we pick steel, plastic, glass or ceramic, and how factories turn raw materials into fertiliser. Every useful product also has a cost, so we weigh benefit against harm and manage the risk.

8. Elective series 3: Developing chemical science

Research advances; chemistry as interdisciplinary science; chemical engineering

• Chemistry Frontiers: Catalysts, New Materials and Chemical Plants – Modern chemistry works with physics, biology, engineering and computing. It makes new molecules (often with catalysts), builds new materials and batteries, and scales reactions up in chemical plants where the leftovers are recycled.

9. 高考 review

Comprehensive review

Coming soon