Chemistry AQA AS Flashcards
Key facts revision
Absolute zero
The lowest possible temperature theoretically achieveable -273.15 degrees celius or zero Kelvin
Absolute temperature
Temperature measured in Kelvin
Acceleration
The stage in mass spectrometry where positive ions are speeded up by an electric field
Acid rain
Rain that has been acidified by pollutants such as sulfur dioxide
Actual yield
Mass of product obtained in a reaction
Addition polymer
Polymer formed when many small unsaturated molecules join together
Addition reaction
The adding together of two or more more to form one larger molecule
Aldehyde
An organic compound containing the -CHO functional group
Alkaline earth metal
An element from group 2 of the periodic table
Alkane
A saturated hydrocarbon with the general molecular formula CnH2n
Allotrope
Allotropes are different forms of the same element that exist in the same physical state. Diamond and graphite are allotropes of carbon
Alloy
A mixture of two or more metals or a mixture of metal and a non metal
Alpha particle
A particle consisting of two protons and two neutrons ejected from a nucleus
Amine
An organic compound that contains nitrogen atom joined to one or more carbon atoms and two or less hydrogen atoms
Amount of substance
The number of particles present, symbol n. It is measured in mole, mol
Anion
A negatively charged ion attracted to the anode during electrolysis
Antacid
A base taken as a medicine to neutralise excess stomach acid
Aromatic
Containing one or more benzene rings
Atom
The smallest particle of an element that has the properties of that element
Atom economy
The proportion of reactants that are converted into useful products rather than waste products
Atomic number
The number of protons in the nucleus of an atom, symbol Z
Atomic radius
The distance from the centre of the nucleus to the outer electrons of an atom
Aufbau principle
The building up process that describes the filling of atomic orbitals in order of increasing energy
Avogadro constant
The number of particles in one mole of a substance- 6.022*10^23
Avogadro’s principle
The idea that equal volumes of gases contain the same number of molecules under the same conditions of temperature and pressure
Axial atom
Atom positioned at the top or bottom of a trigonal bipyramidal molecule
Barometer
An instrument for measuring atmospheric pressure
Base peak
The tallest peak in a mass spectrum
Batch process
An industrial process that is started and stopped at intervals. Production of ethanol by fermentation is a batch process
Bent line
The shape of a molecule that contains two bonding pairs and two lone pairs of electrons
Biofuel
A fuel made from the products of living things
Bond angle
The angle between two adjacent bonds on the same atom
Bond
Attractive force between two atoms, ions or molecules
Boyle’s law
The volume of a fixed mass of gas (at a constant temperature) is inversely proportional to its pressure
Burette
Labatory apparatus used to add precise volumes of liquid during a titration
Carbocation
Ion with a positively charged carbon atom
Carbonyl
An organic compound containing the -C+O functional group, found in baldheads and ketones
Carboxyl
An organic compound containing the _COOH functional group
Carboxylic acid
Organic acids with the general formula RCOOH. Their names end in -oic acid
Cation
A positively charged ion, attracted to the cathodde during electrolysis
CFC
Abbreviation for chloroflurocarbon, a hydrocarbon in which some or all the hydrogen atoms are replaced by chlorine and fluorine atoms
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
Charge density
The charge: size ratio of an ion. Small ions with high charges have large charge densities
Charle’s law
The volume of a fixed mass of gas (at constant pressure) is proportional to its aboslute temperature
Coke
Solid produced by heating coal in the absence of air, almost pure carbon
Complete combustion
Burning a fuel in excess oxygen. Carbon dioxide and water vapour are produced from the complete combustion of hydrocarbons
Concordant results
Titres that are in agreement usually within 0.10cm3 of each other
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
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
Covalent bond
A shared pair of electrons
Cracking
A process used by the petroleum industry to produce shorter alkanes and alkenes from longer alkanes
Cyclic
Hydrocarbons in which there are closed rings of carbon atoms are described as cyclic
D block
The central section of the periodic table between groups 2 and 3 containing the transition metals
Dative covalent bond
Another name for a coordinate bond
Decomposition reaction
A reaction where one substance is broken down into two or more different substances
Deflection
The stage in mass spectrometry where positive ions are moved from their original path by a magnetic field
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
Delocalized
Electrons that are free to move between all atoms in a structure are delocalized. Delocalized electrons are found in metals and graphite
Detection
The stage in mass spectrometry where positive ions reach a detector and produce an electrical signal
Diastereoisomers
Stereoisomers that are mirror images of each other, sometimes called geometrical isomers
Diatomic
A molcule containing just two atoms
Dimer
A molecule consisting of two monomer molecules joined together
Dipole
Opposite charges separated by a short distance in a molecule or ion
Displace
To replace an atom or ion in a compound in a chemical reaction eg chlorine displaces iodine in sodium iodide
Displayed formula
A chemical formula showing all the atoms in a compound and their bonds
Disproportionate
The simultaneous oxidation and reduction of a species
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
Double covalent bond
A bond in which two atoms are joined by two shared pairs of electrons
Ductile
Easily pulled into a thin wire
Electrolysis
The decomposition of a compound into simpler substances using an electric current
Electron gun
The source of high- energy electrons used to ionize the sample in mass spectrometry
Electron-deficient
An atom with a vacant orbital
electro negativity
The power of an atom to withdraw electron density from a covalent bond
Electrophile
A species that can accept a pair of electrons
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
Electrostatic
Involving opposite charges
Elimination reaction
A reaction in which a small simple molecule is removed from a compound forming a double covalent bond.
Empirical formula
A formula that gives the simplest whole number ratio of atoms of each element in a compound
Endothermic
A reaction in which heat energy is absorbed from the surroundings
Endpoint
Where the indicator just changes colour in a titration
Energy level
A certain fixed amount of energy that electrons in an atom can have also called a shell
Equatorial atom
Atom positioned around the middle of a trigonal bipyramidal molecule
Equivalence point
In an acid-base titration the point where equal numbers of moles of hydrogen ions and hydroxide ions have reacted
Excess
More than the amount of reactant needed in a reaction
Feedstock
Raw material used in a manufacturing process
Fermentation
the process for making ethanol from sugar using yeast
Fingerprint region
The part of an infrared spectrum that is unique to a particular compound
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
Flue gas desulfurization
Removing sulfur compounds from waste gases produced by combustion
Flue gas
Waste gases from the combustion of a fuel for example in a power station
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
Fractional distillation
A method of separating mixtures of liquids or gases according to their boiling temperatures
Free radical
A species that contains an unpaired electron produced by homolytic fission of a covalent bond
Frequency
The number of waves per second measured in hertz, Hz
Functional group
An atom, or group of atoms in a molecule which determines its chemical properties
Gas constant
The constant used in the ideal gas equation. Symbol R and is approximately 8.31JK^-1mol^-1
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
Greenhouse effect
Absorption of thermal energy by certain gases in the atmosphere keeping the planet warmer than it would be otherwise
Greenhouse gas
An atmospheric gas that traps infrared raiation that would otherwise be radiated from the earth’s surface into space
Halide ion
A negatively charged ion formed when a halogen atom gains an electron
High resolution mass spectroemter
Device capable of measuring relative atomic masses and relative molecular masses to a high degree of precision
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
Homolytic fission
Breaking of a covalent bond so that each atom takes one electron from the shared pair becoming a radical
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
Hydration
The addition of water across a double bond
Hydrocarbon
A compound containing hydrogen and carbon atoms only
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
Hydrolysis
The splitting of a compound by reaction with water
Hydroxyl group
An -OH group, the functional group found in alcohols
Ideal gas equation
The equation that describes the relationship between pressure, volume, amount of substance and absolute temperature of a gas pV=nRT
Incomplete combustion
Burning of a fuel in a restricted amount of oxygen
Indicator
A substance that changes colour according to the pH of a solution
Induced dipole
An uneven distribution of charge in a molecule or atom caused by a charge in an adjacent particle
Infrared radiation
Electromagnetic radiation with a lower frequency than visible light, felt as heat
Infrared absorption spectrum
Spectrum produced when infrared radiation of various frequencies is absorbed by covalent bonds in a molecule
Infrared spectroscopy
Method used to analyze compounds by their absorption of infrared radiation
Initiation
The first stage in a free radical reaction
Intermediate
Unstable species produced during a reaction before the final product is made
Intermolecular force
Weak attractive force between molecules
Ionic bond
Electrostatic force of attraction between oppositely charged ions
Ionic radius
The distance from the centre of the nucleus to the outer electrons of an ion
Ionization
Producing an electrically charged particle by adding or removing electrons from an atom or molecule
Ionized
An atom or molecule that has gained or lost electrons is said to be ionized
Isoelectronic
Having the same electrong formula but different structural formulae
Kelvin
The unit of absolute temperature symbol K
Ketone
An organic compound containing the carbonyl functional group -C=O and with the general formula R1COR2
Lattice
A regular arrangement of atoms, ions or molecules in a structure
Limiting reactant
A reactant that is completely used up before the other reactants are converted into products
Linear molecule
A molecule with all of its atoms in a straight line
Lone pair
A pair of electrons in the highest occupied energy level that are not used in bonding
Malleable
Can be bent or hammered into shape without breaking
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
Mass spectrum
The output from a mass spectrometer plotting relative abundance against mass to charge ratio m/z
Mass to charge ratio
The mass of an ion divided by its charge symbol m/z
Metallic bond
The electrostatic force of attraction between metal ions and the delocalized electrons in a metallic lattice
Metalloid
Element with properties that are intermediate between the properties of a metal and the properties of a non metal
Molar volume
The volume occupied by one mole of gas at a specified temperature and pressure
Molarity
The concentration of a solution measured in moles of solvent per cubic decimetre of solution mol dm^-3
Molecular crystal
Covalent molecules held together in a regular arrangement by intermolecular forces
Molecular ion
In mass spectrometry the ion that produces a peak in a mass spectrum at the highest m/z value
Molecular sieve
Porous materials such as zeolites that let some molecules pass through but not others
Monoprotic
An acid containing one replaceable hydrogen ion such as Hcl and HNO3
Nitrile
An organic compound containing the -C=-tripleN functional group
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
Nucleophile
A species with a lone pair of electron that is available to form a coordinate bond
Nucleophilic substitution
A chemical reaction in which one nucleophile replaces another in a molecule
Orbital
The volume of space in an atom where one or two electrons are most likely to be found
Ore
A mineral from which metals can be extracted and purified
Ozone
An allotrope of oxygen with the formula 03
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
Pauli exclusion principle
The idea that an orbital cannot hold more than two electrons
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
Permanent dipole-dipole forces
Attractive forces that exist between polar molecules
Polar bond
A covalent bond between atoms with different electro negativities
Polarized
Having opposite charges separated by a small distance
Polyatomic ion
An ion containing more than one atom
positional isomerism
A type of isomerism where the functional group can be joined at different places on the carbon skeleton
Precipitate
An insoluable solid formed when two solutions are mixed
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
Propagation
The stage in a free radical mechanism where a particular radical is used in one reaction then produced again in a subsequent reaction
Reaction mechanism
A step by step description of how a reaction happens
Roast
Heating strongly in a steam of air usually apllied to metal ores
Saturated
A compound containing only single covalent bonds between carbon atoms
Semiconductor
A substance that is an electrical insulator at room temperature but a conductor when warmed or when other elements are added to it
Solute
The substance that will dissolve in a solvent
Solvent
The substance in which a solute will dissolve
Spectator ion
An ion that appears on both sides of an equation but does not take part in the reaction
Standard solution
A solution whose exact molarity is known
Standard temperature and pressure
273K and 100kPa
Stereoisomer
Moelcules with the same structural formula but a different arrangement of their bonds in space
Stratosphere
Upper part of the atmosphere
Structural isomerism
When two or more compounds have the same molecular formulae but different structures
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
Sublime
To pass directly from the solid state to the gas state
Substitution
The replacement of one atom or group of atoms in a molecule by another atom or group of atoms
Temporary dipole
The asymmetrical distribution of the electron pair in a covalent bond
Termination
The final stage in a free radical substitution reaction
Theoretical yield
The maximum mass of product possible calculated using th emas sof reactants and the balanced equation
Thermal cracking
The thermal decomposition of hydrocarbons to produce shorter alkanes and alkenes
Titrant
The solution added from the burette in a titration
Titration
Method used to find the concentration of a sample using a reactant og known concentration
Titre
The volume of titrant added to reach the end point in a titration
Trigonal bipyramial
The shape of a molecule with 5 bonding pairs of electrons
Trigonal planar
The shape of a molecule with 3 bonding pairs of electrons
Trigonal pyramidal
The shape of a molecule with 3 bonding pairs and 1 lone pair of electrons
Unburned hydrocarbons
Pollutants in the exhaust from car engines due to incomplete combustion of the fuel
Unsaturated
Containing at least one carbon- carbon double bond
Valence shell
The energy level in an atom that is involved in forming bonds
Van der waals forces
Temporary induced dipole-dipole attractions between covalent moelcules
Volatile
A liquid that easily vaporizes is said to be very volatile
Volumetric flask
An item of glassware used to make up a standard solution. Also called a graduated/standard flask
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
Zeolite
Compound of aluminium, silicon and oxygen with microscopic pores. Zeolites are used as catalysts and molecular sieves in the petrochemical industry
