Romania Clasa a XI-a Chemistry (technological, 1 h)
Chapters: 3
1. Classes of organic compounds
Compounds with monovalent groups · Compounds with di- and trivalent groups · Compounds with mixed groups · Optical isomerism
- Functional Groups: Halogen, Hydroxyl and Amine Compounds – A functional group is an atom or small group of atoms that replaces a hydrogen on a carbon chain and decides how the compound behaves. Halogen compounds (R–X) have a polar C–X bond. Hydroxyl compounds (R–OH) form hydrogen bonds, so they boil high; phenols are weakly acidic. Amines (R–NH2) have a lone pair on nitrogen, so they are bases.
- 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.
- 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.
- Isomerism in Coordination Compounds – Isomers have the same formula but a different arrangement of atoms. In structural isomers the bonds themselves are different: ionisation, linkage, coordination and solvate isomers. In stereoisomers the bonds are the same but the positions in space differ: geometrical (cis-trans, fac-mer) and optical (mirror images that cannot overlap).
2. Reactions of organic compounds
Substitution · Addition · Elimination and rearrangement · Alkylation, polymerisation and condensation · Hydrolysis and esterification · Yield and conversion
- Basics of Organic Reaction Mechanism – A reaction mechanism is the step-by-step story of which bonds break, which form, and where the electrons move. A covalent bond can break in two ways. In homolysis each atom takes one electron and free radicals form. In heterolysis one atom takes both electrons, giving a carbocation (C with + charge) and a carbanion or an anion. Electron-poor species that seek electrons are electrophiles; electron-rich species that give electrons are nucleophiles. The movement of electrons inside a molecule is controlled by four effects: the inductive effect (pull along σ bonds), the resonance effect (spreading of π electrons), the electromeric effect (a temporary full shift when a reagent attacks) and hyperconjugation (σ C–H electrons spreading into a nearby empty p orbital or π bond). These effects decide how stable an intermediate is and where a reagent attacks.
- 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.
- Types of Organic Reactions and Their Mechanisms – Organic reactions are sorted by what happens to the molecule: substitution (one atom swaps for another), addition (atoms join across a double bond), elimination (a small molecule leaves and a double bond forms), condensation (two molecules join and lose water) and hydrolysis (water splits a molecule). The mechanism shows how electrons move: bonds break homolytically (radicals) or heterolytically (ions), and nucleophiles (electron-rich) attack electrophiles (electron-poor). Esters form from acids and alcohols in a reversible, acid-catalysed condensation and are split by hydrolysis.
- Stoichiometry, Limiting Reagent and Concentration Terms – Stoichiometry means measuring the amounts of substances in a reaction. A balanced equation acts like a recipe: its numbers give the mole ratio of reactants and products. With it you can change any mass into moles, use the ratio, and change back to the mass of any other substance. The reactant that runs out first is the limiting reagent; it decides how much product forms. For solutions, concentration is given as mass percent, mole fraction, molarity or molality.
3. Biologically important compounds; biochemistry
Nucleic acids · Importance of organic products
- 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.
- Organic Products in Industry, Environment and the Body – Organic compounds make our plastics, fibres, fuels, medicines and solvents. Some halogen products, like freons (CFCs), reach the stratosphere and destroy ozone because one chlorine atom can break thousands of ozone molecules. In the body, hydrolysis splits big food molecules and oxidation of glucose releases energy. Proteins fold into primary, secondary and tertiary structures, and the shape lets enzymes speed up reactions and hormones carry messages.