O Level Combined Science Chemistry, 5076
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The List of Definitions
I. Experimental Chemistry
1. Experimental Chemistry
Rate of Reaction—The rate at which reactants are used or products are formed.Distillation—Method of separation of liquid mixtures into its pure liquid factions, by using their boiling points.Factional Distillation—Method of separation of liquid mixtures into its pure liquid factions, whose boiling points are very close.Chromatography—A method of separating and identifying components of a mixture by using its solubility and molecular adhesion to a special paper.Filtration—Used to separate and insoluble or undissolved solid from a liquid.Evaporation & Crystallisation—To separate a dissolved solid from a solution as well-formed crystals.Anions—Negatively charged ions.Cations-Positively charged ions.
II. Atomic Structure & Stoichiometry
2. The Particulate Nature of Matter
Matter—Anything that has mass and occupies space (volume)Solids—A state of matter whose particles are tightly packed, with strong inter-particle forces therefore have high density, fixed shape and volume and are not compressible.Liquids—A state of matter whose particles are loosely packed, with a weak inter-particle forces therefore particles can slide, have no fixed shape but fixed volume and are very slightly compressible.Gases—A state of matter whose particles are far apart, with negligible inter-particle forces therefore particles no fixed shape and volume and are very compressible.Melting—Change of state from solid to liquid at a fixed temperature called the melting point and occurs when the forces of attraction between the particles in the solid are broken.Freezing—Change of state from liquid to solid at a fixed temperature called the freezing point.Boiling—Change of state from liquid to gas at a fixed temperature Particles in the liquid gain enough energy to free from the inter-particle forces and escape into gaseous state. Takes place at the boiling point.
3. Formula, Stoichiometry & the Mole Concept
RAM—The Relative Atomic Mass of an element is the average mass of one atom of the element when compared with 1/12 of the mass of an atom of carbon 12.RMM—The Relative Molecular Mass of a compound is the average mass of one molecule of the substance when compared with 1/12 of the mass of one atom of carbon-12.Mole—A unit of measurement in chemistry where 1 mole of the elementary entities (atoms, molecules, ions, etc) has 6×1023 elementary entities.Solution—Is what you get when a solute dissolves in a solvent.Solute—Is the substance that gets dissolved in a liquid.Solvent—It is the liquid that dissolves the solute.Concentration—The amount of solute that is dissolved in per unit volume of the solvent.
III. Chemistry of Reactions
4. Energy Changes
Endothermic—Heat energy absorbed from surrounding.Exothermic—Heat energy released or given out during the reaction.
5. Chemical Reaction
Chemical Reaction— The phenomenon that is said to have occurred when molecules/atoms split, break up or join to form new ones.Oxidising Agent—-An oxidising agent oxidises the other reactant while itself gets reduced and therefore can be used to identify a reducing agent.Reducing Agent—- Reduces the other reactant while itself gets oxidised and therefore can be used to identify an oxidising agent.
6. Acids, Bases & Salts
Acid—A substance that produces H+ ions when dissolved in water (aqueous solution).Base—Oxides & hydroxides of metals.Alkali—A substance that produces OH- ions when dissolved in water. It is also called a soluble base.Neutralisation—Is the process when an acid and an alkali reacts to form salt and water. The H+ ions from the Acid is neutralised by the OH- ions from the Alkali.pH—A numerical scale that indicates the acidity or basicity of a substance.
7. The Periodic Table
Periodic Table—A table of elements arranged into columns and rows in ascending proton numbers.Alkali Metals—Group 1 elements from the periodic tableHalogens—Group 7 elements from the periodic table.Nobel Gases—Group 0 elements from the periodic table. They are inert gases.
Ductile—Can be stretched wires, e.g. Cu, Au ornamentsMalleable—Can be beaten or hammered into thin sheets, molds and containersAlloys—Mixture of a metal with another element (metal or non-metal) to bring about a physical & chemical advantage to the metal which is dominant in the mixture.Ore—A metal ore is a rock from which the metal can be extracted. The metal ore is a rock that contains the metal in mineral form, from which economically viable amounts of metal can be extracted.
Air—A mixture of gases that surrounds the earth.Pollutant—-A pollutant is a substance which is either harmful or dangerous to lives and/or properties.Greenhouse Effect—The heating up of the earth due to the polluting gases reflecting the thermal radiation from the earth back to the earth thereby increasing the temperature.
IV. Organic Chemistry
10. Organic Chemistry
Organic Chemistry—The study of chemicals found in organisms or derived from it.Hydrocarbon—-A compound that has only hydrogen and carbon in it.Fractional Distillation—A separating technique for separating the constituents of a liquid mixture into various factions depending on their boiling points.Crude Oil—A mixture of hydrocarbons of different carbon numbers (number of carbon atoms) and molecule lengths extracted from the depths of the earth, formed by decayed organic matter under pressure over a long period of time.Homologous Series—A series of organic molecules that come from the same family with the same general formula with a predictable trend in their physical and chemical properties E.g. Alkanes, Alkenes, Alcohols and Carboxylic Acids.Functional group—The group of atoms unique to a homologous series of organic compounds that determine the physical and chemical properties of the series. Only some homologous series have a “functional group”. E.g. Alcohols and Carboxylic AcidsCracking—Process of breaking down heavy Alkanes (with large molecules) to form hydrocarbons of smaller molecules (Alkanes and Alkenes) and other wanted products.Unsaturated Hydrocarbons—Hydrocarbons with double or more bonds between their carbon atoms.Polymers—Large chained molecules that have a repeating pattern in their arrangement.Polymerisation—Is the chemical reaction when large numbers of similar small molecules (monomers) are joined together to form a big molecule (polymer).Polyunsaturated—Polymers (giant molecules) that are unsaturated, i.e. have double or more bonds between their carbon atoms. e.g. vegetable oil.
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