Ukraine 11 клас Chemistry (profile level)
Chapters: 4
1. Review and deepening of theory
Atomic structure · Periodic trends · Bonding and structure · Solutions and redox
- Quantum Mechanical Model: Quantum Numbers, Orbitals and Configuration – Moving electrons also behave like waves: λ = h/mv (de Broglie). Because of this we cannot know exact position and momentum together: Δx·Δp ≥ h/4π (Heisenberg). So we drop sharp orbits and use orbitals: regions where the electron is likely to be, from the Schrödinger equation (ψ² gives probability). Four quantum numbers describe each electron: n (shell, size, energy), l (subshell, shape: 0 to n−1), mₗ (orientation: −l to +l) and mₛ (spin: +½ or −½). s is spherical, p is dumbbell, d is mostly four-lobed. Electrons fill by the Aufbau (n + l) rule, Pauli principle (max 2, opposite spins) and Hund's rule (single first). Half-filled and fully filled subshells are extra stable, so Cr is 3d⁵4s¹ and Cu is 3d¹⁰4s¹.
- Periodic Trends in Properties – Two forces decide almost every trend: the pull of the nucleus (effective nuclear charge) and the distance of the outer shell. Across a period the nuclear pull grows while the shell stays the same, so atoms shrink, ionisation enthalpy rises, electron gain enthalpy becomes more negative and electronegativity rises. Down a group a new shell is added, so atoms grow and these values fall. Cations are smaller and anions bigger than their atoms. Valence follows the outer electrons; metallic reactivity is highest at the bottom left and non-metallic reactivity at the top right.
- Valence Bond Theory and Hybridisation – Valence bond theory says a covalent bond forms when half-filled orbitals of two atoms overlap and the two electrons pair up with opposite spins. Head-on overlap makes a strong σ (sigma) bond; side-on overlap of p orbitals makes a weaker π (pi) bond. To explain real shapes, an atom first mixes its orbitals into equal hybrid orbitals: sp (linear, 180°), sp² (trigonal planar, 120°), sp³ (tetrahedral, 109.5°), sp³d (trigonal bipyramidal) and sp³d² (octahedral).
- Redox Reactions: From Oxygen to Electron Transfer – Oxidation first meant adding oxygen or removing hydrogen. Reduction meant the opposite. Today we use a bigger idea: oxidation is losing electrons and reduction is gaining electrons. Both always happen together, so we call them redox reactions. A more active metal gives electrons to the ion of a less active metal.
2. Non-metallic elements and compounds
Hydrogen · Halogens · Chalcogens · Group VA elements · Group IVA elements
- Hydrogen: The Lightest Element – Hydrogen (H) is element 1: one proton and one electron. It exists as H₂ molecules, a colourless, odourless gas that is the least dense of all gases and hardly dissolves in water. In the lab it is made from a reactive metal and a dilute acid (Zn + 2HCl → ZnCl₂ + H₂) and collected over water. It burns with a squeaky pop to form only water. It reacts with non-metals to give hydrides such as HCl, NH₃ and H₂S, and it reduces some metal oxides. It has three isotopes: protium, deuterium and tritium. Uses: ammonia and fertilisers, margarine, rocket fuel and clean fuel cells.
- Halogens: The Group 17 Elements – The halogens are fluorine, chlorine, bromine, iodine and astatine, in group 17 of the periodic table. Each atom has 7 outer electrons, so it gains 1 electron to form a halide ion (X⁻). Down the group, atoms get bigger, colours get darker, melting and boiling points rise, and reactivity falls. A more reactive halogen displaces a less reactive one from its salt.
- Sulfur and Its Compounds – Sulfur (S, atomic number 16, electrons 2, 8, 6) is a yellow non-metal in group 16 with oxygen. Solid sulfur is made of S₈ rings and has rhombic and monoclinic forms. It burns to sulfur dioxide (SO₂), a gas that bleaches, kills microbes and causes acid rain. In the contact process SO₂ is oxidised to SO₃ over a V₂O₅ catalyst and turned into sulfuric acid (H₂SO₄), a strong acid that also dehydrates and oxidises. Hydrogen sulfide (H₂S) smells of bad eggs. Sulfate ions are found with barium chloride: a white precipitate of BaSO₄ that does not dissolve in dilute HCl.
- Nitrogen and Its Compounds – Nitrogen gas (N₂) makes up 78% of air. Its triple bond makes it very unreactive, so plants cannot use it directly. Fixation turns N₂ into compounds: lightning and bacteria do it naturally, and the Haber process makes ammonia (NH₃) industrially. Ammonia is a basic gas that forms ammonium salts. At high temperature N₂ and O₂ form NO, which becomes brown NO₂; NO₂ in rain makes nitric acid and acid rain. Nitric acid is a strong acid and oxidising agent used for fertilisers.
3. Metallic elements and compounds
General properties of metals · Group IA–IIIA metals · Iron
- Metallurgy: From Metallic Bond to Getting Metals Out of Ores – Metals are made of positive ions held in a sea of free electrons. This metallic bond explains why they shine, conduct and bend. Most metals are found in rocks as compounds called ores. Metallurgy is the science of getting a pure metal out of its ore: first concentrate the ore, then turn the compound into metal by heat (pyrometallurgy), by solutions (hydrometallurgy) or by electricity (electrometallurgy), then refine it. The more reactive a metal is, the harder it is to extract and the faster it corrodes.
- Alkali Metals and Sodium Compounds – Alkali metals (lithium, sodium, potassium, rubidium, caesium) are group 1 of the periodic table. Each atom has one outer electron that it loses easily, forming M⁺ ions. They are soft, light and very reactive: they react with water to make hydrogen and an alkali, and they burn in air. Reactivity rises down the group. Sodium gives Na₂O, Na₂O₂, Na₂CO₃ (washing soda) and NaHCO₃ (baking soda), and each metal colours a flame in its own way.
- Transition Elements (d-Block) – Transition elements are the d-block metals of groups 3 to 12. Their last electron goes into an inner (n−1)d orbital. Because the d-orbitals are only partly filled, they show many oxidation states, coloured ions, magnetism (μ = √(n(n+2)) BM), good catalytic power and easy alloy formation.
4. General review of chemistry
Basic laws and theories · Bonding and complex compounds · Chemical reactions · Dispersed systems · Chemistry in society
- Laws of Chemical Combination and Dalton's Atomic Theory – Five laws describe how elements combine. Mass is conserved in a reaction. A compound always has the same elements in the same mass ratio. When two elements make more than one compound, the masses of one that join a fixed mass of the other are in a small whole-number ratio. Reacting gases have volumes in simple whole-number ratios, and equal volumes of gases hold equal numbers of molecules. Dalton's atomic theory explains all of these with atoms.
- Coordination Compounds: Werner's Theory, Terms and IUPAC Names – A coordination compound has a central metal atom or ion joined to a fixed number of ions or molecules called ligands. Each ligand gives one pair of electrons to the metal. The metal and its ligands sit together inside square brackets, the coordination sphere. The number of donor atoms bonded to the metal is the coordination number. Werner said a metal shows two kinds of valence: primary (ionisable, outside the bracket) and secondary (fixed, inside the bracket).
- Enthalpy, Calorimetry and Hess's Law – Enthalpy H = U + pV. At constant pressure the heat taken in or given out equals ΔH; at constant volume it equals ΔU. We measure ΔU in a sealed bomb calorimeter and ΔH in an open cup calorimeter, using q = C ΔT or q = m c ΔT. For gases, ΔH = ΔU + Δn_g RT. The reaction enthalpy ΔrH is negative for exothermic and positive for endothermic reactions, and ΔrH° = ΣΔfH°(products) − ΣΔfH°(reactants). Hess's law: the total enthalpy change is the same whether a reaction happens in one step or many, so thermochemical equations can be added like algebra.
- Colloids and Dispersed Systems – A dispersed system is one substance spread as small bits (the dispersed phase) through another (the dispersion medium). By particle size it is a true solution (below about 1 nm), a colloid (about 1–100 nm) or a suspension (above about 100 nm). Colloid particles are too small to see or to settle, but big enough to scatter light, so a beam passing through shows its path: the Tyndall effect. Colloids are grouped by the states of the two phases (fog, smoke, milk, foam, gel). Colloid particles often carry the same charge and repel each other; adding an electrolyte cancels the charge, so they clump and settle: coagulation.
- Science, Technology and Society: How Discoveries Change Our Lives – Science finds out how nature works; technology uses that knowledge to make tools and solve problems. Society shapes science too, by asking questions, paying for research and making rules. Big changes such as the printing press, the steam engine, electricity, vaccines and the internet changed how people work, live and think. Every technology has benefits and risks. To decide wisely we look at evidence, weigh benefits against risks, ask who gains and who loses, think about ethics and the future, and use safety rules.