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Flashcards in Chemistry AQA AS Deck (193):
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Absolute temperature

Temperature measured in Kelvin

1

Absolute zero

The lowest possible temperature theoretically achieveable -273.15 degrees celius or zero Kelvin

2

Acceleration

The stage in mass spectrometry where positive ions are speeded up by an electric field

3

Acid rain

Rain that has been acidified by pollutants such as sulfur dioxide

4

Actual yield

Mass of product obtained in a reaction

5

Addition polymer

Polymer formed when many small unsaturated molecules join together

6

Addition reaction

The adding together of two or more more to form one larger molecule

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Aldehyde

An organic compound containing the -CHO functional group

8

Alkaline earth metal

An element from group 2 of the periodic table

9

Alkane

A saturated hydrocarbon with the general molecular formula CnH2n

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Allotrope

Allotropes are different forms of the same element that exist in the same physical state. Diamond and graphite are allotropes of carbon

11

Alloy

A mixture of two or more metals or a mixture of metal and a non metal

12

Alpha particle

A particle consisting of two protons and two neutrons ejected from a nucleus

13

Amine

An organic compound that contains nitrogen atom joined to one or more carbon atoms and two or less hydrogen atoms

14

Amount of substance

The number of particles present, symbol n. It is measured in mole, mol

15

Anion

A negatively charged ion attracted to the anode during electrolysis

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Antacid

A base taken as a medicine to neutralise excess stomach acid

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Aromatic

Containing one or more benzene rings

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Atom

The smallest particle of an element that has the properties of that element

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Atom economy

The proportion of reactants that are converted into useful products rather than waste products

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Atomic number

The number of protons in the nucleus of an atom, symbol Z

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Atomic radius

The distance from the centre of the nucleus to the outer electrons of an atom

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Aufbau principle

The building up process that describes the filling of atomic orbitals in order of increasing energy

23

Avogadro constant

The number of particles in one mole of a substance- 6.022*10^23

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Avogadro's principle

The idea that equal volumes of gases contain the same number of molecules under the same conditions of temperature and pressure

25

Axial atom

Atom positioned at the top or bottom of a trigonal bipyramidal molecule

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Barometer

An instrument for measuring atmospheric pressure

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Base peak

The tallest peak in a mass spectrum

28

Batch process

An industrial process that is started and stopped at intervals. Production of ethanol by fermentation is a batch process

29

Bent line

The shape of a molecule that contains two bonding pairs and two lone pairs of electrons

30

Biofuel

A fuel made from the products of living things

31

Bond angle

The angle between two adjacent bonds on the same atom

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Bond

Attractive force between two atoms, ions or molecules

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Boyle's law

The volume of a fixed mass of gas (at a constant temperature) is inversely proportional to its pressure

34

Burette

Labatory apparatus used to add precise volumes of liquid during a titration

35

Carbocation

Ion with a positively charged carbon atom

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Carbonyl

An organic compound containing the -C+O functional group, found in baldheads and ketones

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Carboxyl

An organic compound containing the _COOH functional group

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Carboxylic acid

Organic acids with the general formula RCOOH. Their names end in -oic acid

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Cation

A positively charged ion, attracted to the cathodde during electrolysis

40

CFC

Abbreviation for chloroflurocarbon, a hydrocarbon in which some or all the hydrogen atoms are replaced by chlorine and fluorine atoms

41

Chain isomerism

A type of structural isomerism in which compounds have identical molecular formulae but their carbon atoms are joined together in different arrangments. Chain isomers involve branched and unbranched carbon chains

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Charge density

The charge: size ratio of an ion. Small ions with high charges have large charge densities

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Charle's law

The volume of a fixed mass of gas (at constant pressure) is proportional to its aboslute temperature

44

Coke

Solid produced by heating coal in the absence of air, almost pure carbon

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Complete combustion

Burning a fuel in excess oxygen. Carbon dioxide and water vapour are produced from the complete combustion of hydrocarbons

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Concordant results

Titres that are in agreement usually within 0.10cm3 of each other

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Continous process

An industrial process in which products are made all the time without any break. Production of iron in the blast furnace is a continuous process

48

Co-ordinate bond

A covalent bond in which the shared pair of electrons is provided by only one of the bonded atoms. In the bond X_>Y, X provides both electrons

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Covalent bond

A shared pair of electrons

50

Cracking

A process used by the petroleum industry to produce shorter alkanes and alkenes from longer alkanes

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Cyclic

Hydrocarbons in which there are closed rings of carbon atoms are described as cyclic

52

D block

The central section of the periodic table between groups 2 and 3 containing the transition metals

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Dative covalent bond

Another name for a coordinate bond

54

Decomposition reaction

A reaction where one substance is broken down into two or more different substances

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Deflection

The stage in mass spectrometry where positive ions are moved from their original path by a magnetic field

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Dehydration reaction

A reaction where elements hydrogen and oxygen are removed from a reactant in the ratio of 2:1 effectively the removal of water

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Delocalized

Electrons that are free to move between all atoms in a structure are delocalized. Delocalized electrons are found in metals and graphite

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Detection

The stage in mass spectrometry where positive ions reach a detector and produce an electrical signal

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Diastereoisomers

Stereoisomers that are mirror images of each other, sometimes called geometrical isomers

60

Diatomic

A molcule containing just two atoms

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Dimer

A molecule consisting of two monomer molecules joined together

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Dipole

Opposite charges separated by a short distance in a molecule or ion

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Displace

To replace an atom or ion in a compound in a chemical reaction eg chlorine displaces iodine in sodium iodide

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Displayed formula

A chemical formula showing all the atoms in a compound and their bonds

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Disproportionate

The simultaneous oxidation and reduction of a species

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Dot and cross diagram

A diagram showing all of the bonding electrons in a molecule. The electrons in one atom are shown as dots and the electrons in the other atom are shown as crosses

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Double covalent bond

A bond in which two atoms are joined by two shared pairs of electrons

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Ductile

Easily pulled into a thin wire

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Electrolysis

The decomposition of a compound into simpler substances using an electric current

70

Electron gun

The source of high- energy electrons used to ionize the sample in mass spectrometry

71

Electron-deficient

An atom with a vacant orbital

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electro negativity

The power of an atom to withdraw electron density from a covalent bond

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Electrophile

A species that can accept a pair of electrons

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Electrophilic addition

A reaction in which an electrophile is attracted to a region of high electron density such as a carbon-carbon double bond and adds on to an atom or group

75

Electrostatic

Involving opposite charges

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Elimination reaction

A reaction in which a small simple molecule is removed from a compound forming a double covalent bond.

77

Empirical formula

A formula that gives the simplest whole number ratio of atoms of each element in a compound

78

Endothermic

A reaction in which heat energy is absorbed from the surroundings

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Endpoint

Where the indicator just changes colour in a titration

80

Energy level

A certain fixed amount of energy that electrons in an atom can have also called a shell

81

Equatorial atom

Atom positioned around the middle of a trigonal bipyramidal molecule

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Equivalence point

In an acid-base titration the point where equal numbers of moles of hydrogen ions and hydroxide ions have reacted

83

Excess

More than the amount of reactant needed in a reaction

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Feedstock

Raw material used in a manufacturing process

85

Fermentation

the process for making ethanol from sugar using yeast

86

Fingerprint region

The part of an infrared spectrum that is unique to a particular compound

87

First ionization energy

The energy needed to remove one mole of electrons from one mole of gaseous atoms forming one mole of ions with a single positive charge

88

Flue gas desulfurization

Removing sulfur compounds from waste gases produced by combustion

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Flue gas

Waste gases from the combustion of a fuel for example in a power station

90

Fraction

A part of a mixture collected at a particular temperature range by fractional distillation. A crude oil fraction contains hydrocarbons with a similar chain length

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Fractional distillation

A method of separating mixtures of liquids or gases according to their boiling temperatures

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Free radical

A species that contains an unpaired electron produced by homolytic fission of a covalent bond

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Frequency

The number of waves per second measured in hertz, Hz

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Functional group

An atom, or group of atoms in a molecule which determines its chemical properties

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Gas constant

The constant used in the ideal gas equation. Symbol R and is approximately 8.31JK^-1mol^-1

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Giant covalent

A structure in which very many atoms are joined by covalent bonds to form a regular structure. Diamond and graphite have giant covalent structures

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Greenhouse effect

Absorption of thermal energy by certain gases in the atmosphere keeping the planet warmer than it would be otherwise

98

Greenhouse gas

An atmospheric gas that traps infrared raiation that would otherwise be radiated from the earth's surface into space

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Halide ion

A negatively charged ion formed when a halogen atom gains an electron

100

High resolution mass spectroemter

Device capable of measuring relative atomic masses and relative molecular masses to a high degree of precision

101

Homologous series

A series od compounds with the same general formula and functional group. Each member differs from the next by the presence of one more -CH2 group

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Homolytic fission

Breaking of a covalent bond so that each atom takes one electron from the shared pair becoming a radical

103

Hund's rule

Only when all the orbitals in a particular sub level contain an electron do electrons begin to ccupy the orbitals in pairs

104

Hydration

The addition of water across a double bond

105

Hydrocarbon

A compound containing hydrogen and carbon atoms only

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Hydrogen bond

An intermolecular force between a lone pair of electrons on an N, O or F atom in one molecule and an H atom joined to an N, O or F atom in another molecule

107

Hydrolysis

The splitting of a compound by reaction with water

108

Hydroxyl group

An -OH group, the functional group found in alcohols

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Ideal gas equation

The equation that describes the relationship between pressure, volume, amount of substance and absolute temperature of a gas pV=nRT

110

Incomplete combustion

Burning of a fuel in a restricted amount of oxygen

111

Indicator

A substance that changes colour according to the pH of a solution

112

Induced dipole

An uneven distribution of charge in a molecule or atom caused by a charge in an adjacent particle

113

Infrared radiation

Electromagnetic radiation with a lower frequency than visible light, felt as heat

114

Infrared absorption spectrum

Spectrum produced when infrared radiation of various frequencies is absorbed by covalent bonds in a molecule

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Infrared spectroscopy

Method used to analyze compounds by their absorption of infrared radiation

116

Initiation

The first stage in a free radical reaction

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Intermediate

Unstable species produced during a reaction before the final product is made

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Intermolecular force

Weak attractive force between molecules

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Ionic bond

Electrostatic force of attraction between oppositely charged ions

120

Ionic radius

The distance from the centre of the nucleus to the outer electrons of an ion

121

Ionization

Producing an electrically charged particle by adding or removing electrons from an atom or molecule

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Ionized

An atom or molecule that has gained or lost electrons is said to be ionized

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Isoelectronic

Having the same electrong formula but different structural formulae

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Kelvin

The unit of absolute temperature symbol K

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Ketone

An organic compound containing the carbonyl functional group -C=O and with the general formula R1COR2

126

Lattice

A regular arrangement of atoms, ions or molecules in a structure

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Limiting reactant

A reactant that is completely used up before the other reactants are converted into products

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Linear molecule

A molecule with all of its atoms in a straight line

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Lone pair

A pair of electrons in the highest occupied energy level that are not used in bonding

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Malleable

Can be bent or hammered into shape without breaking

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Mass spectrometer

An instrument used to determine the relative atomic mass of an element or relative molecular mass of a compound. The structure of a complex molecule can be worked out by analysis of a mass spectrum

132

Mass spectrum

The output from a mass spectrometer plotting relative abundance against mass to charge ratio m/z

133

Mass to charge ratio

The mass of an ion divided by its charge symbol m/z

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Metallic bond

The electrostatic force of attraction between metal ions and the delocalized electrons in a metallic lattice

135

Metalloid

Element with properties that are intermediate between the properties of a metal and the properties of a non metal

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Molar volume

The volume occupied by one mole of gas at a specified temperature and pressure

137

Molarity

The concentration of a solution measured in moles of solvent per cubic decimetre of solution mol dm^-3

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Molecular crystal

Covalent molecules held together in a regular arrangement by intermolecular forces

139

Molecular ion

In mass spectrometry the ion that produces a peak in a mass spectrum at the highest m/z value

140

Molecular sieve

Porous materials such as zeolites that let some molecules pass through but not others

141

Monoprotic

An acid containing one replaceable hydrogen ion such as Hcl and HNO3

142

Nitrile

An organic compound containing the -C=-tripleN functional group

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Non polar

Having no dipole. A molecule with polar bonds may be non polar if its shape is such that the dipoles cancel each other out

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Nucleophile

A species with a lone pair of electron that is available to form a coordinate bond

145

Nucleophilic substitution

A chemical reaction in which one nucleophile replaces another in a molecule

146

Orbital

The volume of space in an atom where one or two electrons are most likely to be found

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Ore

A mineral from which metals can be extracted and purified

148

Ozone

An allotrope of oxygen with the formula 03

149

Ozone layer

The part of the atmosphere with the greatest concentration of ozone. Found in the stratosphere it absorbs harmful ultraviolet radiation from the sun

150

Pauli exclusion principle

The idea that an orbital cannot hold more than two electrons

151

Pauling electro negativity scale

A scale showing the ability of elements to withdraw electron density from a covalent bond. The larger the number the more electronegative the element

152

Permanent dipole-dipole forces

Attractive forces that exist between polar molecules

153

Polar bond

A covalent bond between atoms with different electro negativities

154

Polarized

Having opposite charges separated by a small distance

155

Polyatomic ion

An ion containing more than one atom

156

positional isomerism

A type of isomerism where the functional group can be joined at different places on the carbon skeleton

157

Precipitate

An insoluable solid formed when two solutions are mixed

158

Primary haloalkane

An haloalkane with one carbon atom or where the carbon atom carrying the halogen atom is directly attached to just one other carbon atom

159

Propagation

The stage in a free radical mechanism where a particular radical is used in one reaction then produced again in a subsequent reaction

160

Reaction mechanism

A step by step description of how a reaction happens

161

Roast

Heating strongly in a steam of air usually apllied to metal ores

162

Saturated

A compound containing only single covalent bonds between carbon atoms

163

Semiconductor

A substance that is an electrical insulator at room temperature but a conductor when warmed or when other elements are added to it

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Solute

The substance that will dissolve in a solvent

165

Solvent

The substance in which a solute will dissolve

166

Spectator ion

An ion that appears on both sides of an equation but does not take part in the reaction

167

Standard solution

A solution whose exact molarity is known

168

Standard temperature and pressure

273K and 100kPa

169

Stereoisomer

Moelcules with the same structural formula but a different arrangement of their bonds in space

170

Stratosphere

Upper part of the atmosphere

171

Structural isomerism

When two or more compounds have the same molecular formulae but different structures

172

Sub level

Part of an energy level in an atom containing pairs of electrons
S sub levels contain up to one electron pair
P sub levels contain up to three electron pairs
D sub levels contain up to five electron pairs

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Sublime

To pass directly from the solid state to the gas state

174

Substitution

The replacement of one atom or group of atoms in a molecule by another atom or group of atoms

175

Temporary dipole

The asymmetrical distribution of the electron pair in a covalent bond

176

Termination

The final stage in a free radical substitution reaction

177

Theoretical yield

The maximum mass of product possible calculated using th emas sof reactants and the balanced equation

178

Thermal cracking

The thermal decomposition of hydrocarbons to produce shorter alkanes and alkenes

179

Titrant

The solution added from the burette in a titration

180

Titration

Method used to find the concentration of a sample using a reactant og known concentration

181

Titre

The volume of titrant added to reach the end point in a titration

182

Trigonal bipyramial

The shape of a molecule with 5 bonding pairs of electrons

183

Trigonal planar

The shape of a molecule with 3 bonding pairs of electrons

184

Trigonal pyramidal

The shape of a molecule with 3 bonding pairs and 1 lone pair of electrons

185

Unburned hydrocarbons

Pollutants in the exhaust from car engines due to incomplete combustion of the fuel

186

Unsaturated

Containing at least one carbon- carbon double bond

187

Valence shell

The energy level in an atom that is involved in forming bonds

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Van der waals forces

Temporary induced dipole-dipole attractions between covalent moelcules

189

Volatile

A liquid that easily vaporizes is said to be very volatile

190

Volumetric flask

An item of glassware used to make up a standard solution. Also called a graduated/standard flask

191

VSEPR

Valence shell electron pair repulsion theory. The theory used to predict the shape of a covalent molecule using the idea of repulsion by pairs of electrons

192

Zeolite

Compound of aluminium, silicon and oxygen with microscopic pores. Zeolites are used as catalysts and molecular sieves in the petrochemical industry