AQA Chemistry Unit 2 Keywords

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  • Created by: Sam_98
  • Created on: 24-02-14 21:48
A sour substance that can attack metal, clothing or skin. The chemical opposite of an alkali. When dissolved in water, its solution has a pH of less than 7. Acids are proton (H+ Ion) donors
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Activation energy
The minimum energy needed to start off a reaction
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Its solution has a pH of more than 7
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Describes a substance that does not contain water
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Aqueous solution
Mixture made by adding a soluble substance to water
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Atomic Number
The number of protons in an atom
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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. (Base dissolved in water). Bases are Proton (H+ ion) acceptors
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A substance that speeds up a chemical reaction. At the end of the reaction the catalyst is chemically unchanged
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The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as absorbent paper
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Collision Theory
An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for the reaction to take place
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Covalent Bonding
The attraction between two atoms that share one or more pairs of electrons
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Delocalised electron
Bonding electron that is no longer associated with any one particular atom
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Dot and Cross diagrams
A drawing to show the arrangement of the outer shell electrons only of the atoms or ions in a substance
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A liquid, containing free moving ions, that is broken down by electricity in the process of electrolysis
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Empirical Formula
The simplest ratio of elements in a compound
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A reaction that takes in energy from the surroundings
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A reaction that gives out energy to the surroundings
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Form of the element carbon that can form a large cage like structure based on hexagonal rings of carbon atoms
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Gas Chromatography
The process of separating the components in a mixture by passing the vapours through a column and detecting them as they leave the column at different times
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Giant Covalent Structure
A huge 3D network of covalently bonded atoms
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Giant lattice or structure
A huge 3D network of atoms or ions
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Change of the quantity plotted on the y-axis divided by the quantity plotted on the x-axis
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Describes a substance that contains water in its crystals
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Intermolecular force
the attraction between the individual molecules in a covalently bonded substance
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A charged particle produced by the loss or gain of electrons
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Ionic Bonding
The electrostatic force of attraction between positively and negatively charged ions
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Atom that has the same number of protons but different number of neutrons
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Giant Covalent Structure
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Mass Number
The number of Protons plus neutrons in the nucleus of an atom
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Mass spectrometer
a machine that can be used to analyse small amounts of a substance to identify it and to find its relative molecular mass
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The amounts of a substance in the relative atomic or formula mass of a substance in grams
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Molecular Formula
The chemical formula that shows the actual numbers of atoms in a particular molecule
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Molecular Ion Peak
The peak on the mass spectrum of a substance which tells us the relative molecular mass of the substance. The peak is produced by the heaviest positive ion shown on the mass spectrum
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The study of very tiny particles or structures between 1 and 100 nanometres in size
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A solution with a pH value of 7 that is neither acidic nor an alkaline. Alternatively, something that carries no overall electrical charge
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The chemical reaction of an acid with a base in which they cancel each other out,forming a salt and water. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction
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The reaction when oxygen is added to a substance, or when electrons are lost
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Percentage yield
The actual mass of product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100
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pH Scale
A number that shows how strongly acidic or alkaline a solution is. Acids have a pH value of less than 7, alkalis have a pH value above 7
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An insoluble solid formed by a reaction taking place in solution
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A reaction in which oxygen is removed, or electrons are gained
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Relative atomic mass, Ar
The average mass of the atoms of an element compared with carbon-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 ration shown in the chemical formula, of a substance
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Retention time
The time it takes a component in a mixture to pass through the column during gas chromatography
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Reversible Reaction
A reaction in which the products can re-form the reactants
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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
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Shape Memory Alloy
Mixture of metals which respond to changes in temperature
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State symbol
The abbreviations used in balanced symbol equations to show if reactants and products are solid, liquid, gas or aqueous
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Thermal decomposition
The breakdown of a compound using heat
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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 heat, then remoulded into different shapes as they cool down and set
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Universal indicator
A mixture of indicators which can change through a range of colours depending on the pH of a solution. Its colour is matched to a pH number using a pH scale. It shows how strongly acidic or alkaline liquids and solutions are
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Card 2


The minimum energy needed to start off a reaction


Activation energy

Card 3


Its solution has a pH of more than 7


Preview of the back of card 3

Card 4


Describes a substance that does not contain water


Preview of the back of card 4

Card 5


Mixture made by adding a soluble substance to water


Preview of the back of card 5
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