Chemistry Key Words

A measurement is considered accurate if it is judged to be close to the true value
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When dissolved in water, its solution has a pH value less than 7. Acids are proton (H+ ion) donors.
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Activation energy
The minimum energy needed for a reaction to take place
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Alkali metal
Elements in Group 1 of the periodic table
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Its solution has a pH value more than 7
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Saturated hydrocarbon with the general formula CnH2n+2, e.g. methane, ethane and propane
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Unsaturated hydrocarbon which contains a carbon-carbon double bond. Its general formula in CnH2n, e.g. ethene, C2H4.
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A mixture of two or more elements, at least one of which is a metal
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Describes a substance that does not contain water
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The positive electrode in electrolysis
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Results that do not match the pattern seen in the other data collected or are well outside the range of other repeat readings (outliers)
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Aqueous solution
The mixture made by adding a soluble substance to water
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The relatively thin layer of gases that surround planet Earth
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The smallest part of an element that can still be recognised as that element
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Atom economy
A measure of the amount of starting materials that end up as useful products
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Atomic number
The number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number.
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Avagrado constant
The number of atoms, molecules, or ions in a mole of any substance (i.e., 6.02 * 10*23 per mol).
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Balanced symbol equations
A symbol equation in which there are equal numbers of each type of atom on either side of the equation
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The oxide, hydroxide, or carbonate of a metal that will react with an acid, forming a salt as one of the products. (If a base dissolves in water it is called an alkali). Bases are proton (H+ ion)
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Materials that can be broken down by microorganisms
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Fuel made from animal or plant products
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Blast furnace
The huge reaction vessels used in industry to extract iron from its ore
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Bond energy
The energy required to break a specific chemical bond
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A long glass tube with a tap at one end and markings to show volumes of liquid; used to add precisely known volumes of liquids to a solution in a conical flask below it.
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Carbon footprint
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
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Carbon steel
Alloy of iron containing controlled, small amounts of carbon
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Categoric variable
Categoric variables have values that are labels, e.g. types of material
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A substance that speeds up a chemical reaction by providing a different pathway for the reaction by providing a different pathway for the reaction that has a lower activation energy. The catalyst is chemical unchanged at the end of the reaction.
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Catalytic converter
Fixed to exhausts of vehicles to reduce pollutants released
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The negative electrode in electrolysis
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Materials made by heating clay, or other compounds, to high temperatures (called firing) to make hard, but often brittle, materials, which make excellent electrical insulators
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The process whereby small amunts of dissolved substances are separated by running a solvent along a material such as absorbent paper
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Climate change
The change in global weather patterns that could be caused by excess levels of greenhouse gases in the atmosphere
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Closed system
A system in which no matter enters or leaves
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Collision theory
An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for a reaction to take place
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Materials made of two or more different materials, containing a matrix or binder surrounding and binding together fibres or fragments of another material which act as the reinforcement.
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A substance made when two or more elements are chemically bonded together
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Continuous variable
Can have values (called a quantity) that can be given by measurement (e.g., mass, volume, temperature, etc.).
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Continuous data
Data that can take on any value
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Control group
If an experiment is to determine the effect of changing a single variable, a control is often set up in which the independent variable is not changed, thus enabling a comparison to be made.
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(Control group continued)
If the investigation is of the survey type a control group is usually established to serve the same purpose.
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Control variable
A variable which may, in addition to the independant variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
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Covalent bond
The bond between two atoms (non-metals) that share one or more pairs of electrons
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Covalent bonding
The attraction between two atoms (non-metals) that share one or more pairs of electrons
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The reaction between two atoms that share one or more pairs of electrons
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Information, either qualitative or quantitative, that has been collected.
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Delocalised electron
Bonding electron that is no longer associated with any one particular atom
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Dependant variable
The variable for which the value is measured for each and every change in the independent variable
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The automatic mixing of liquids and gases as a result of the random motion of their particles
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Directly proportional
A relationship that, when drawn on a line graph, shows a positive linear relationship that crosses through that origin
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Discrete data
Data that can only take certain values
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Displacement reaction
A reaction in which a more relative elements takes the place of a less reactive element in one of its compounds or its solution
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Separation of a liquid from a mixture by evaporation followed by condensation
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Dot and cross diagram
A drawing to show only the arrangement of the outer shell electrons of the atoms or ions in a substance
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DNA (deoxyribonucleic acid)
A large organic molecule that encodes genetic instructions for the development and functioning of living organisms and viruses
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Double bond
A covalent bond made by the sharing of two pairs of electrond
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Electrical (chemical) cells
Contain chemicals that react to produce electricity
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The breakdown of a substance containing ions by electricity
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A liquid, containing free-moving ions, which is broken down by electricity in the process of electrolysis
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A tiny particle with a negative charge. Electrons orbit the nucleus of atoms or ions in shells
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Electronic structure
A set of numbers to show the arrangement of electrons in their shells (or energy levels)
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A substance made up of only one type of atom. An element cannon be broken down chemically into any simpler substance
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End point
The point in a titration where the reaction is complete and titration should stop
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A reaction that takes in energy from the surroundings
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The point in a reversible reaction at which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant
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A reaction that transfers energy to the surroundings
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Fair test
A fair test is one in which only the independent variable has been allowed to affect the dependent variable
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The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide
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The technique used to separate substances that are insoluble in a particular solvent from those that are soluble
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Flame emission spectroscopy
A method of instrumental analysis in which the light given off when a sample is placed in a flame produces characteristic line spectra to identify and measure the concentration of metal ions in the sample
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Easily ignited and capable of burning rapidly
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a mixture that has been designed as a useful product
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Hydrocarbons with similar boiling points separated from crude oil
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Fractional distillation
A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids
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Fuel cells
Sources of electricity that are supplied by an external source of fuel
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Form of the element carbon that can exist as large cage-like structures, based on hexagonal rings of carbon atoms
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Functional group
An atom or group of atoms that give organic compounds their characteristic reactions
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Iron or steel objects that have been protected from rusting by a thin layer of zinc metal at their surface
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Giant covalent structure
A huge 3D network of covalently bonded atoms
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Giant lattice
A huge 3D network of atoms or ions
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Giant structure
See giant lattice
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A measure of the slope of a straight line on a graph
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All the elements in the columns (labelled 1-7 and 0) in the periodic table
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Half equation
An equation that describes reduction (gain of electrons) or oxidation (loss of electrons) OIL RIG-Oxidation Is Loss Reduction Is Gain
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group 7 of the periodic table. They're a group of toxic non-metals that have coloured vapours. They have low melting points & boiling points, their melting & boiling points increase going down the group. They're poor conductors of heat & electricity.
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Something (e.g. an object, a property of a substance or an activity) that can cause harm
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Homologous series
A group of related organic compounds that have the same functional group
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Describes a substance that contains water in its crystals
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A compound containing only hydrogen and carbon
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A proposal intended to explain certain facts or observations
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Incomplete combustion
When a fuel burns insufficient oxygen, producing carbon monoxide as a toxic product
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Independent variable
The variable for which values are changed or selected by the investigator
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Intermolecular forces
The attraction between the individual molecules in a covalently bonded surface
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A charged particle produced by the loss or gain of electrons
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Ionic bond
The electrostatic force of attraction between positively and negatively charged ions
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Ionic equation
An equation that shows only those ions or atoms that change in a chemical reaction
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Atoms that have the same number of protons but different number of neutrons, i.e, they have the same atomic number but different mass numbers
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Law of the conservation of energy
The total mass of the products formed in a reaction is equal to the total mass of the reactants
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Le Chatelier's Principle
When a change in conditions is introduced to a system at equilibrium, the position of equilibrium shifts so as to cancel out the change
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Life cycle assessment
Carried out to assess the environmental impact of products, processes or services at different stages in their life cycle
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Line graph
Used when both variables are continuous. The line should normally be a line of best fit, and may be straight or a smooth curve
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Line of best fit
A straight line that represents the general trend of data. An equal number of data points should be above and below the line of best fit
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Mass number
The number of protons plus the number of neutrons in the nucleus of an atom
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The arithmetical average of a series of numbers
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When some elements or compounds are mixed together and intermingle but do not react together (i.e., no new substance is made). A mixture is not a pure substance
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The amount of substance in the relative atomic or formula mass of a substance in grams. no. of moles=mass(g)/Ar, number of moles of gas=volume of gas(dm cubed)/24dm cubed
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Molecular formula
The chemical formula that shows that actual numbers of atoms in a particular molecule
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Small reactive molecules that react together in repeating sequences to form a very large molecule (a polymer)
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The study of very tiny particles or structures between 1 and 100 nanometres in size - where 1 nanometre = 10 to the power of -9 metres
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A solution with a pH value of 7 which is neither acidic nor alkaline. Alternatively, something that carries no overall electrical charge
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The chemical reaction of an acid with a base in which a salt and water are formed. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction
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A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge
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Noble gases
The very unreactive gases found in Group 0 of the periodic table. Their atoms have very stable electronic structures as they all have full outer shells
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Something which cannot be replaced once it is used up
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Nucleus (of an atom)
The very small and dense central part of an atom that contains protons and neutrons
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Order of magnitude
A comparison of the size of values. Two values are the same order of magnitude if their difference in size is small in comparison to other values being compared
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Ore is rock which contains enough metal to make it economically worthwhile to extract the metal
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\the reaction when oxygen is added to a substance / or when electrons are lost
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Describes a substance that has had oxygen added to it / or has lost electrons
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Small solid particle given off from motor vehicles as a result of incomplete combustion of its fuel
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Percentage yield
The acual mass of a product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100, percentage yield= actual mass of product produced/ maximum theoretical mass of production possible
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A number which shows how strongly acidic or alkaline a solution is
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A glass tube used to measure accurate volumes of liquids
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A substance made from very large molecules made up of many repeating units
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An insoluble solid formed by a reaction taking place in solution
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A substance made as a result of a chemical reaction
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A tiny positive particle found inside the nucleus of an atom
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Qualitative data
Data that is descriptive or categorical
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Quantitative data
Data that is numerical or a measurement
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A substance we start with before a chemical reaction takes place
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Reaction profile
The relative difference in the energy of reactants and products
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Reactivity series
A list of elements in order of their reactivity
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The process in which waste materials are processed to be used again
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A reaction in which oxygen is removed or electrons are gained
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The link between the variables that were investigated
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Relative atomic mass Ar
The average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element
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Relative formula mass Mr
The total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance
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A measurement is repeatable if the original experimenter repeates the investigation using the same method and equipment and obtains the same or precise results
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A measurement is reproducible if the investigation is repeated by another person, using different equipment and the same results are obtained
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The process by which food molecules are broken down to release energy for the cells
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Reversible reaction
A reaction in which food molecules are broken down to release energy for the cells
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Rr(retention factor)
A measurement from chromotography: it is the distance a spot of substance has been carried above the baseline divided by the distance of the solvent front
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The corrosion of iron
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Sacrificial protection
An effective way to prevent rusting whereby a metal more reactive than iron (such as zinc or magnesium) is attached to or coated on an object
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A salt is a compound formed when some or all of the hydrogen in an acid is replaced by a metal. Formulae: metal + acid-> a salt + hydrogen, acid+ base -> a salt + water, acid + alkali -> a salt + water
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Saturated hydrocarbon
Describes a hydrocarbon with only single bonds between its carbon atoms. This means that it contains as many hydrogen atoms as possible in each molecule
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AN area in an atom, around its nucleus, where electrons are found
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SI system of units
A system of units for physical quantities that are considered the standard units
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Stainless steel
A chromium-nickel alloy of steel which does not rust
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Standard form
A way of displaying large and small numbers
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State symbol
The abbreviations used in balanced symbol equations to show if reactants and products are solid (s), liquid (l), gas (g), or dissolved in water (aq)
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Strong acids
These acids completely ionise in aqueous solutions
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Thermal decomposition
The breakdown of a compound by heating it
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Thermosetting polymer
Polymer that can form extensive cross-linking between chains, resulting in rigid materials which are heat-resistant
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Thermosoftening polymer
Polymer that forms plastics which can be softened by heating, then remoulded into different shapes as they cool down and set
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A method for measuring the volumes of two solutions that react together
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Transition element
Element from the central block of the periodic table
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Universal indicator
A mixture of indications that can change through a range of colours to show how strongly acidic or alkaline liquids and solutions are
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Unsaturated hydrocarbon
A hydrocarbon whose molecules contains at least one carbon-carbon double bond
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Physical, chemical or biological quantity or characteristic
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The resistance of a liquid to flowing or pouring; a liquids 'thickness'
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Weak acids
Acids that do not ionise completely in aqueous solutions
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Other cards in this set

Card 2


When dissolved in water, its solution has a pH value less than 7. Acids are proton (H+ ion) donors.



Card 3


The minimum energy needed for a reaction to take place


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Card 4


Elements in Group 1 of the periodic table


Preview of the back of card 4

Card 5


Its solution has a pH value more than 7


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