Japan 高校1年 Basic Chemistry
Chapters: 3
1. Chemistry and human life
Chemistry and substances
- Mixtures and Their Separation – A mixture has two or more substances mixed without any fixed ratio, and each keeps its own properties. Homogeneous mixtures (solutions) look the same everywhere; heterogeneous ones do not. By particle size we get solutions (< 1 nm), colloids (1–1000 nm) and suspensions (> 1000 nm). Colloids scatter light (Tyndall effect). Concentration tells how much solute is in a solution. We separate mixtures by using a difference in their parts: evaporation, crystallisation, distillation, chromatography, sublimation, centrifugation and coagulation.
2. Composition of substances
Constituent particles · Chemical bonding
- Structure of the Atom – An atom has a tiny, heavy, positive nucleus made of protons and neutrons. Electrons move around it in fixed shells K, L, M, N. The number of protons (Z) tells the element; protons + neutrons give the mass number (A). Outer electrons decide valency. Isotopes share Z; isobars share A.
- Kossel-Lewis Approach and the Ionic Bond – Atoms join so that each gets a stable outer shell of 8 electrons (an octet), like a noble gas. Kossel said atoms can give or take electrons to make ions (ionic bond). Lewis said atoms can also share pairs of electrons (covalent bond). Lewis structures show these electrons as dots and lines. Formal charge (V − L − B/2) helps pick the best Lewis structure. Ions pack into a crystal, and the energy released is linked to the lattice enthalpy.
3. Chemical change and its uses
Amount of substance and equations · Chemical reactions · World opened by chemistry
- Mole Concept, Molar Mass and Chemical Formulas – Atoms are far too small to count one by one, so chemists count them by weighing. Atomic masses are given in u, where 1 u is one-twelfth the mass of a carbon-12 atom. One mole is 6.022 × 10²³ particles, and its mass in grams equals the formula mass in u. With moles we can find the percentage of each element in a compound, and work back from percentages to the empirical and molecular formulas.
- Acids and Bases: Properties, Indicators and Reactions – An acid gives H⁺ ions in water and a base gives OH⁻ ions. Indicators show which one is present by a colour or smell change, and when H⁺ meets OH⁻ they make water, leaving a salt behind.