Chemistry Keywords - Table Format

CH-17 Solid liquids and gases Matter - Anything that occupies space and has mass. Evaporation - The changing of a liquid to a gas. Condensation - The changing of a gas back into its liquid state. Diffusion - The movement of particles from an area of high concentration to an area of low concentration. Solids - Particles are closely packed together, don’t move but can vibrate, have a definite volume and shape. Liquids - Particles are close to each other but are free to move around, they have a definite volume but their shape can change. Gases - Particles are free to move in all directions, they don’t have a definite shape or volume and spread out to fill a container they're placed in, and they can be compressed easily since they’re spread out. CH-18 Solutions and Crystallisation Crystallisation - The formation of crystals by cooling a saturated solution. Solute - The substance being dissolved. Solvent - The liquid the solute is dissolving in. Solution - The solute and the solvent. Soluble - The ability to for a substance to dissolve in a solvent. Insoluble - A substance that can’t dissolve. Solubility - How much will dissolve. Concentrated solution - A large amount of solute in a small amount of solvent. Saturated solution - A solution that contains as much dissolved solute as possible at that temperature. CH-19 Separating mixtures Mixture - Consists of two or more substances mingled together but not chemically combined. Filtering - Used to separate an insoluble solid from a liquid. Evaporation - Used to retrieve a solute from a solution. Distillation - Used to separate substances that have different boiling points. Chromatography - Used to separate a mixture of substances which are in a solution. CH-20 Elements, compounds and mixtures An element - A substance made up of only one type of atom. A molecule - Composed of two or more atoms chemically combined. Compounds - Consist of two or more elements chemically combined. CH-21 The atom An atom - The smallest part of an element which still has the properties of that element. Atomic number - The number of protons in an atom of that element. The mass number - The total number of protons and neutrons in an atom of that element. Isotopes - Atoms of the same element which have different numbers of neutrons. Protons - Positive and found in the nucleus. Neutrons - Neutral and found in the nucleus. Electrons - Negative and orbit the nucleus. CH-22 The periodic table The periodic table - Show the elements in order of increasing atomic numbers. Groups - Vertical columns of elements. Periods - Horizontal rows of elements in the periodic table. CH-23 Chemical bonding An ionic bond - The force of attraction between oppositely charged ions in a compound. An ion - A Charged atom or group of atoms. A covalent bond - Formed when electrons are shared between non-metal atoms. CH-24 Metals and non-Metals Alloy - A mixture of metals. Rusting - The corrosion of iron. Metals - Hard, dense, shiny, have high melting points, good conductors, malleable, ductile and sonorous. Non-Metals - Usually opposite to metals. CH-25 Fuels Fuels - A substance that burns in oxygen to produce heat. Fossil fuels - Formed from the remains of organisms that lived millions of years ago. Hydrocarbons - Compounds made up of hydrogen and carbon. CH-26 Acids and Bases Acids - Have a PH less than 7, sour taste and turn blue litmus red. Bases - Have a PH greater than 7, tastes bitter and turns red litmus blue. Alkali - A base that is soluble in water. The PH scale - A measure of acidity or basicity, running from 0 to 14. Neutral substance - PH of 7, eg. Water. Titrations - A way of neutralising a base and acid restoring the balance. CH-27 The Atmosphere Catalysts - Substances that alter the rate of a chemical reaction but are not used up themselves by allowing particles with less energy an alternative path with a lower activation energy. Air - Contains 78% nitrogen, 21% oxygen, CO2 and water vapour. CH-28 Water Electrolysis - The splitting up of a compound by passing electricity through it. The meniscus - The curved surface of a liquid in a vessel. Water - A compound made up of hydrogen and oxygen. Desalination - A process that obtains freshwater from seawater(saltwater). CH-29 Water Hardness Hard water - Does not lather easily with soap and contains calcium and magnesium ions. Soft water - Lathers easily with soap. CH-30 Plastics Polymerisation - Small repeating units called monomers join together to form a larger molecule called a polymer. Plastics - Man-made materials, mostly from crude oil. Fractional distillation - Separates various hydrocarbons found in crude oil. Non-Biodegradable - They remain intact for long periods of time.