C1 exam: Key words to understand There are lots of new key terms that you need to make sure you understand in preparation for your exam. It’s really important that you recognise what each of the words mean and are able to use them correctly in a sentence. This will help you to explain ideas scientifically and ensure you pick up important marks in your exam. Some tips for learning science vocabulary. Tip 1 -Play some games with the keywords You could play hangman with your friends or family using the words you need to learn. Make sure you explain what the word means when they have guessed it. You could play Pictionary for some of the energy types or renewable energy sources. Ask someone to draw you a picture for one of these terms and see if you can guess which one they are drawing. Tip 2 – Use flash cards Write out the key word and the definition on separate cards, mix them up and see if you can match the keyword with the correct description. Write the keyword on one side and the definition on the other. Look at the keyword side and see if you can remember the definition or read the definition and try to remember the keyword. Turn the card over to check, or ask someone else to read them out to you. See if you can sort the keywords into groups of similar words. For example, you could group together all the words that give a different type of energy. Try to explain why you have grouped them together to a friend or family member. Tip 3 – Spelling strategies Use the spelling strategies that you talk about in tutor time to help with any words that you find difficult to spell. Break it into sounds Break it into syllables Break it into word parts Use a mnemonic Refer to word in the same family Say it as it sounds Words within words Make connections between words Think about the meaning of words Apply spelling rules Learn by sight (d-i-a-r-y) (re-mem-ber, con-tin-ent) (dis+satisfy) (necessary—one collar, two sleeves, rhythm has your two hips moving) (muscle—muscular) (Wed-nes-day) (Parliament—I AM parliament, GUM in argument) (bright, light, night, etc) (bi+cycle = two+wheels) (writing, written) (look—cover—write—check) Topic 1 – The Earth’s sea and atmosphere Key term What it means Atmosphere Layers of gases that surround the earth Deforestation The destruction of the world’s trees and forests Limestone Sedimentary rock, mostly calcium carbonate made from the remains of marine organisms Noble gases Unreactive gases in Group 0 of the periodic table Photosynthesis Set of chemical reactions in plants that allow them to produce their own food (glucose) using water and carbon dioxide and releasing oxygen as a waste product. This process is powered by light from the Sun. Sedimentary rock Rock made by compression of layers of solid material (sediment that settles to the bottom of a fluid, such as water) Trace A small amount of Topic 2 – Materials from the Earth Key term What it means Aqueous solution Mixture forms when a substance dissolves in water. Atom The smallest part of an element that can take part in chemical reactions Balanced equation Description of a reaction using the symbols and formulae of the reactants and products, so that the number of ‘units’ of each element to the left of the arrow is the same as those to the right of the arrow Cement Material made by heating limestone with clay Chalk Sedimentary rock, mostly calcium carbonate, made from the remains of marine micro-organisms Compound A substance containing two or more elements chemically joined together Concrete Material made by mixing cement with sand, stones and water Crystal A solid in which the particles are arranged in an ordered pattern Key term What it means Element Substance that cannot be split up into simpler substances Erosion Removal or transportation of broken up rocks Fossil The preserved traces or remains of an organism that lived a very long time ago Granite Igneous rock with relatively large crystals, formed when magma cools and solidifies slowly Igneous rock Rock formed when magma cools and solidifies Insoluble Substance which does not dissolve in a given solution Lava Molten rock on the Earth’s surface Limewater A solution of calcium hydroxide that turns milky when carbon dioxide is bubbled through it Magma Molten rock inside the Earth’s crust Marble Metamorphic rock, mostly calcium carbonate, formed from limestone or chalk Metamorphic rock Rock formed the action of very hot temperature and pressure on other rocks Neutralisation reaction Reaction in which a base or alkali reacts with an acid Quarry Shallow mine on the Earth’s surface from where rocks are removed Precipitate Insoluble solid formed when two solutions are mixed together and a precipitation reaction occurs Precipitation reaction A reaction in which an insoluble product is formed from soluble reactants Product Substance formed by a chemical reaction Rate How quickly something happens Reactant Substance used up in a chemical reaction Solidifies To become solid Soluble Substance which dissolves in a given substance Key term What it means State symbols Letter or letters to show the state of a substance e.g. (g) for gas) Thermal decomposition Reaction in which one substance breaks down when heated to form two or more new substances Word equation Description of a reaction using the names of the reactants and products Topic 3 - Acids Key term What it means Acid A substance with a pH of less than 7. The stronger the acid, the lower the pH number Alkali Bases that dissolve in water are called alkalis. They are solutions with excess OH- ions and have a pH greater than 7 Alkali metal An element in group 1 of the periodic table Anode Positive electrode Anion A negative ion, produced by gaining electrons (usually a non-metal ion) Antacid A compound that is used to neutralise acid in the stomach Aqueous solution A mixture formed when a substance dissolves in water Balanced equation Bases Description of a reaction using the symbols and formulae of the reactants and products, so that the number of ‘units’ on each side of the reaction is the same Substances that can react with acids and neutralise them to make a salt and water are called bases. They are usually metal oxides or metal hydroxides Boiling point This is the maximum temperature a liquid can achieve. For water, the boiling point is 100oC (at standard atmospheric pressure) Bonds Two elements joined in a chemical bond (types are ionic, covalent and metallic) Cathode A negative electrode Cation A positively charged ion, produced by losing electrons (usually a metal ion) Chemical formula A combination of symbols and numbers that show how many atoms of different kinds are in a particular molecule. In compounds that do not form molecules, it shows the ratio of elements in a compound Key term What it means Compound A substance containing more than one type of atom chemically joined together Concentration A measure of how much solute is dissolved in a solvent. Units are g dm3 or mol dm3 Conductor (electrical) A sample that allows electricity to pass through it Conservation of mass A law that states that no mass is gained or lost in a chemical reaction Corrosion Chemical changes to metals converting them to compounds, as in rusting of iron Corrosive A material that wears away and destroys Current A movement of electrons (or other charged particles) Electricity A flow of charged particles that can be used to transfer energy Electrode A rod made of carbon of conducting metal which carries the current in an electrolyte Electrolysis The process in which an electrical current decomposes a compound Electrolytes Ionic liquid where moving ions carry an electrical current during the process of electrolysis Electron A particle with negligible mass and a charge of -1 Electroplating The process where a metal is coated with a thin coating of another metal using electrolysis Element One type of atom Hazard symbols Symbols used on containers to warn users of its contents Hazardous A substance that could be dangerous if not used or stored properly Indicator A substance which can change colour depending on the pH of a solution Indigestion Pain caused by excess acid in the stomach Insoluble A substance which does not dissolve in a given solvent Ion An atom with an electrical charge Key term What it means Litmus paper Blue litmus paper turns red in acidic solutions and red litmus paper turns blue in alkaline solutions Mixture A substance containing two or more substances that are not chemically joined together Molecule Two or more atoms joined together with a covalent bond Neutralisation reaction Reaction between an acid and a base to form a salt and water Neutron Particle found in the nucleus, with no charge and a mass of 1 pH scale A scale from 1-14 showing acidity or alkalinity Proton Particle found in the nucleus, having a mass of 1 and a charge of +1 Salt Salts are made when an acid reacts with a base, carbonate or metal. The name of the salt formed depends on the metal in the base and the acid used. For example, salts made using hydrochloric acid are called chlorides Universal indicator A mixture of dyes that changes colour gradually over a range of pH and is used in testing for acids and alkalis Topic 4 – Obtaining and using metals Key term What it means Alloy A mixture of different metals Alloy steel Iron that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties Atoms The smallest particle of a chemical element Bonds Two elements joined in a chemical bond (types are ionic, covalent and metallic) Carats A measure of the purity of gold with pure gold being 24 carat Chemical formula A combination of symbols and numbers that show how many atoms of different kinds are in a particular molecule. In compounds that do not form molecules, it shows the ratio of elements in a compound Compound A substance containing more than one type of atom chemically joined together Key term What it means Conduct Allows something to pass through (heat or electricity) Conductor (electrical) A sample that allows electricity to pass through it Density The mass of substance per unit volume (unit is usually g/cm3) Ductile Can be stretched into wires Electricity A flow of charged particles that can be used to transfer energy Electrolysis The process in which an electrical current decomposes a compound Electroplating The process where a metal is coated with a thin coating of another metal using electrolysis Element One type of atom Extraction Reaction in which a metal is produced from a compound in an ore Malleable Can be hammered into shape Melting point The point at which a substance turns from a solid to a liquid Mixture A substance containing two or more substances that are not chemically joined together Ores Rock from which a metal can be extracted for profit Oxidation A reaction in which oxygen is added to a chemical; loss of an electron by a negative ion Reactivity How fast or how readily an element reacts Reactivity series A list of metals arranged in order of reactivity Recycle To extract a metal from waste to be reused or processed to make a new object or material Reduction Occurs when oxygen is removed from a compound. Gain of an electron by a positive ion Rusting The corrosion of iron Shape memory alloy An alloy that returns to its original shape with a change in conditions, often temperature Topic 5 - Fuels Key term What it means Acid rain Rain that is more acidic than normal, has a pH lower than 5.2 Alkane A hydrocarbon in which all the bonds between the carbon atoms are single bonds Alkene A hydrocarbon in which there are one or more double bonds between carbon atoms Biodegradable A substance that can be broken down by microorganisms Biodiesel Diesel fuel made from plant material Biofuel A fuel made from plants or microorganisms Boiling point Temperature at which a substance changes from a liquid to a gas Bonds The way in which atoms in molecules are joined Bromine test A test for unsaturation. Bromine water turns colourless when mixed with an unsaturated molecule. Bromine water A solution of bromine in water that turns colourless when mixed with an unsaturated molecule Carbon monoxide Carbon neutral A toxic gas (CO), it is made during incomplete combustion. It replaces oxygen in the blood and so reduces the amount of oxygen carried around the body Whereby the carbon dioxide added to the atmosphere when the fuel is burnt is only replacing that which was removed from the atmosphere, during photosynthesis, when the plant was growing. Therefore overall no more carbon dioxide is being added to the atmosphere Climate change The idea that the Earth’s climate is changing. Many scientists believe this is linked to increasing carbon dioxide levels Combustion Chemical reaction when substances burn, combining with oxygen to produce heat and waste products such as carbon dioxide Complete combustion Combustion of hydrocarbons with enough oxygen present to convert all the fuel into carbon dioxide and water Cracking A type of chemical reaction in which large alkane molecules are decomposed into two or more smaller molecules to form smaller alkanes and alkenes Crude oil A mixture of hydrocarbons formed from dead microscopic organisms by heat and pressure over millions of years Double bond When two bonds join a pair of the same atoms (usually two carbon atoms) Ethanol A fuel made by processing sugar beet or sugar cane Fossil fuel Non-renewable fuels such as coal, oil and natural gas that have formed over millions of years from dead plants and animals Fractional distillation A method of separating a mixture of liquids with different boiling points into individual components (fractions) Fraction A component of a mixture that has been separated by fractional distillation Fuel cell A device which produces electricity from hydrogen and oxygen without burning Hydrocarbon molecules A compound of hydrogen and carbon only Ignite To start burning Incinerated Burnt, i.e. waste Incomplete combustion Combustion that occurs without enough oxygen to completely oxidise all the fuel. Incomplete combustion of hydrocarbons produces carbon dioxide, carbon monoxide and carbon (soot) Limewater A solution of calcium hydroxide that turns milky when carbon dioxide is bubbled through it Mixture A substance containing two or more different substances that are not joined together Monomer Small molecule used to make a polymer Non-renewable resource Resources that cannot be replaced once they have been used. These will eventually run out Plastics The common name for many polymers Poly(chloroethene) A polymer made from chloroethene monomers. Also known as PVC Poly(ethene) A polymer made from ethane monomers Poly(propene) A polymer made from propene monomers Poly(tetrafluoroethene) The chemical name for PTFE, which is also known as Teflon Polymer A long molecule made by joining many smaller molecules (monomers) together Polymerisation The process of making a polymer Key term Renewable Saturated What it means Something that can be made without diminishing the resources used to make it, such as biofuels made from plants that can be grown again A molecule which contains only single bonds between the carbon atoms and has the maximum possible number of atoms attached to the carbon chain Soot Tiny particles of solid carbon produced by incomplete combustion Unsaturated A molecule which contains one or more double bonds between the carbon atoms, allowing extra atoms to be added on to the carbon chain Viscosity How thick or runny a liquid is. Low viscosity is very runny, high viscosity is thick