Chemistry, 14–17 years — 44 topics · MyLeoNes™ Kuks
44 chemistry topics written for 14–17 years — not a older text simplified. In teaching order, each a deck of five cards: the idea, why it exists, a worked example, the common trap and where you meet it.
Chemistry · 14–17 years
Atoms, elements and compounds
Matter is built from atoms. Understanding the difference between elements, molecules and compounds gives chemistry a map for describing substances.
Conservation in chemical equations
A reaction rearranges atoms rather than making them vanish. Balanced equations show the same number of each kind of atom before and after the change.
Chemical bonding
Atoms join because their electrons can settle into more stable arrangements. Ionic and covalent bonding explain why substances have different structures and properties.
Acids, bases and pH
The pH scale describes how acidic or basic an aqueous solution is. It turns a chemical property into a number that can be tested, compared and used safely.
Moles and molar mass
The mole is chemistry’s way to count enormous numbers of particles by weighing them.
Concentration of solutions
Concentration describes how much dissolved substance is packed into a given volume of solution.
Energy changes in chemical reactions
Chemical reactions can transfer energy to the surroundings or take energy from them.
Reaction rates
Reaction rate describes how quickly reactants are changed into products.
Patterns in the periodic table
The position of an element gives clues about how its atoms behave. Reading these patterns lets you make sensible predictions before carrying out an experiment.
Oxidation and reduction
Many reactions involve electrons moving from one substance to another. Tracking that movement explains rust, batteries and why two reacting substances can change in opposite ways.
Dynamic equilibrium
Some reactions can go forwards and backwards. At equilibrium, both directions continue, but at equal rates, so the amounts stay steady unless conditions change.
Electrolysis
Electrolysis uses electrical energy to force a chemical change that would not happen readily on its own. It is a practical way to split compounds or coat objects with metal.
Hydrocarbons and carbon chains
Carbon can join to itself in chains and rings, making an enormous family of substances.
Functional groups
Small patterns of atoms give organic molecules their characteristic reactions and properties.
Polymers
Many small molecules can join into long chains whose properties make materials such as plastic, rubber and nylon.
Chromatography
Chromatography separates a mixture so its substances can be seen and identified.
Empirical and molecular formulae
How measurements reveal the simplest ratio of atoms in a substance, and how that ratio can be expanded to its real molecular formula.
Reacting quantities
Using a balanced equation as a recipe for converting the amount of one chemical into the amount of another.
The limiting reactant
Why a reaction stops when one reactant runs out, even if other reactants are still left.
Titration
Finding the concentration of an unknown solution by adding a solution of known concentration until the reaction is exactly complete.
Molecular shape and polarity
The atoms in a molecule can pull electrons unevenly, and the molecule’s 3D shape decides whether those pulls cancel or leave one side charged.
Intermolecular forces
Molecules attract one another without forming new covalent bonds. These attractions help explain boiling points, viscosity and surface tension.
Solubility and precipitation
Some substances dissolve only up to a limit. When dissolved particles can no longer stay in solution, a solid may form as a precipitate.
Nuclear decay and half-life
Unstable atomic nuclei can change into more stable ones and release radiation. Half-life describes how quickly a sample changes, not how long one particular atom will last.
Electron configuration and ions
The electrons in an atom are arranged in energy levels. That arrangement helps you predict how atoms form ions and why some elements react more readily than others.
Isomerism
Some molecules have the same molecular formula but different arrangements of atoms. Those different structures can have different shapes, properties and uses.
Catalysts
A catalyst gives a reaction another route with a lower activation energy. It makes the reaction faster without being used up, but it does not change the final equilibrium position.
Mass spectrometry
Mass spectrometry identifies particles by measuring their mass-to-charge ratio. A spectrum can reveal isotopes, molecular masses and fragments, giving evidence about what a sample contains.
Buffer solutions
How a solution resists sudden changes in pH.
Distillation
Separating liquids by using different boiling points.
Infrared spectroscopy
Using infrared light to detect bonds in molecules.
Green chemistry
Designing chemistry to prevent waste and harm from the start.
Measurement uncertainty
Every measurement has a limit to its precision. You learn to report results honestly instead of pretending that an instrument gives more certainty than it can.
Qualitative tests for ions
Some ions can be identified by visible reactions such as a colour, a precipitate or a gas. You learn to use several clues together, because one observation alone can mislead you.
Esters and esterification
An ester forms when an alcohol and a carboxylic acid react, usually making a sweet-smelling molecule and water. The reaction links structure to smell, reversibility and useful materials.
UV-visible spectroscopy
Molecules can absorb particular wavelengths of ultraviolet or visible light. Measuring that absorption helps you investigate colour, concentration and electronic structure without using up much sample.
Atom economy
Atom economy compares how much of the starting materials becomes the useful product. It helps chemists design reactions that waste less.
Calorimetry
Calorimetry uses measured temperature changes to find how much energy a reaction transfers. It turns a warm or cool solution into chemical evidence.
Nuclear magnetic resonance
Nuclear magnetic resonance, or NMR, reveals the chemical surroundings of certain atomic nuclei. Chemists use the pattern of signals to work out how atoms are connected in a molecule.
Soaps and detergents
Soap and detergent molecules have a water-loving end and an oil-loving end. Their shape lets them surround grease and carry it away in water.
Hess's law
Calculate an enthalpy change indirectly by combining reactions whose values are known.
Recrystallisation
Purify an impure solid by dissolving it hot and forming cleaner crystals as it cools.
Amino acids and peptide bonds
See how amino acids join into chains that fold into proteins.
Electrochemical cells
Understand how a spontaneous redox reaction can drive electrons through a wire.
In this section
Keep exploring
Other languages
Loading MyLeoNes™…