ALL DEFINITIONS Flashcards
Acid
A species that is a proton donor.
Activation energy
The minimum energy required to start a reaction by the breaking of bonds.
Addition polymer
A very long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules
Addition reaction
A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
Adsorption
The process that occurs when a gas, liquid or solute is held to the surface of a solid or a liquid(rare).
Alicyclic hydrocarbon
A hydrocarbon with carbon atoms joined together in a ring structure
Aliphatic hydrocarbon
A hydrocarbon with carbon atoms joined together in a straight or branched chain
Alkali
A type of base that dissolves in water forming hydroxide ions, (OH-, aqueous ions)
Alkanes
The homologous series with the general formula CnH2n+2
Alkyl group
An alkane with a hydrogen atom removed (often denoted R)
Amount of Substance
The quantity with unit mole, used for counting atoms
Anhydrous
A substance that contains no water molecules
Anion
A negatively charged ion (no one likes onions-negative anions)
Atom economy
(Mr of desired product)/(Mr of all products) *100%
Atomic orbital
A region within an atom that can hold up to two electrons, with opposite spins
Atomic number
Number of protons in the nucleus of an atom
Average bond enthalpy
Average enthalpy change that takes place when 1 mol of a type of bond in the molecules of a gas are broken by homolytic fission
Avogadro constant (Na)
The number of atoms per mole of the carbon-12 isotope (6.02 *10^23 mol^-1)
Base
A species that is a proton acceptor
Biodegradable material
A substance that is broken down naturally in the enviroment by living organisms
Carbanion
An organic ion in which a carbon atom has a negative charge
Carbocation
An organic ion in which a carbon atom has a positive charge
Catalyst
A substance that increases the rate of chemical reaction without being used up in the process
Cation
A positively charged ion (everyone likes cats)
Cis-trans isomerism
Type of E/Z isomerism, hydrogen and non hydrogen atom on each C in C=C, CIS: hydrogen on same side of bond, TRANS: hydrogen on opposite sides of bond
Concentration
The amount of solute, in mol, per 1 dm^-3 of solution
Coordinate bond
A shared pair of electrons which has been provided by only one of the bonding atoms (aka dative covalent)
Covalent bond
A bond formed by a shared pair of electrons
Cracking
The break down of a long chained saturated hydrocarbon to form a mixture of shorter chained alkanes and alkenes
Curly arrow
Symbol used in reaction mechanisms to show the movement of an electron pair in the breaking or formation of a covalent bond
Dative covalent
A shared pair of electrons which has been provided by only one of the bonding atoms
Dehydration
An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
Delocalised electrons
Electrons that are shared between more than two atoms
Displacement reaction
A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its ions
Disproportionation
The oxidation and reduction of the same element in a redox reaction
Dynamic equilibrium
The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction
E/Z isomerism
A type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently due to restricted rotation of C=C bond
Electron configuration
The arrangement of electrons in an atom
Electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
Electron sheilding
The repulsion between electrons in different inner shells, sheilding reduces the net attractive force from the positive nucleus on the outer shell electrons
Electrophile
An atom, or group, that is attracted to an electron dense space or atom, where it accepts a pair of electrons to form a new covalent bond
Electrophillic addition
A type of addition reaction in which an electrophile is attracted to an electron dense atom, it accepts an electron pair to form a new covalent bond
Elimination reaction
The removal of a molecule from a saturated molecule to make an unsaturated molecule
Emperical formula
The simplest whole number ratio of atoms of each element in a compound
Endothermic reaction
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, results in heat being taken in from the surroundings
Enthalpy
The heat content that is stored in a chemical system
Standard enthalpy change of combustion
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditons, all reactants and products in their standard states
Standard enthalpy of formation
The enthalpy change that takes place when one mole of a compound is formed from its pure elements in their standard states under standard conditions
Standard enthalpy of reaction
The enthalpy change of a reaction in molar quantities expressed in a chemical equation under standard conditions
Enthalpy cycle
Diagram showing alternative routes between reactants and products to allow indirect determination of enthalpy change (from other known enthalpy changes using Hess’ Law)
Enthalpy profile diagram
Diagram comparing enthalpy levels of reactants and products in a reaction
Esterification
The reaction of an alcohol with a carboxylic acid to produce an ester and water
Exothermic reaction
A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, results in heat loss to surroundings
Fractional Distillation
The seperation of components in a liquid mixture into fractions which differ in boiling point by distillation, using a fractionating column
Fragmentation
The process in mass spectrometry that cause a postive ion to split into pieces, one of which is a positive fragment ion
Functional group
The part of the organic molecule responsible for its chemical properties and reactions
General formula
The simplest algebraic formula of a member of a homologous series
Giant covalent lattice
A 3D structure of atoms, bonded together by strong covalent bonds
Giant ionic lattice
A 3D structure of oppositely charged ions, bonded by strong ionic bonds
Giant metallic lattice
A 3D structure of positive ions and delocalised electrons, bonded together by strong metallic bonds
Greenhouse effect
Process in which the absorption and subsequent emission of infrared radiation by the atmospheric gases warms the lower atmosphere and planet’s surface
Hess’ Law
If a reaction can take place by more than one route and the intital and final conditions are the same, the total enthalpy along each route will be the same
Heterogeneous catalysis
A reaction in which the catalyst has a different physical state to the reactants
Homogeneous catalysis
A reaction in which the catalyst and reactants are in the same physical state
Heterolytic fission
Breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation and anion
Homolytic fission
Breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals
Homologous series
A series of organic compounds with the same functional group, but with each sucessive member differing by CH2
Hydrated
Crystalline and containing water molecules
Hydrogen bond
A strong dipole attraction between an electron deficient hydrogen atom on one molecules and a lone pair of electrons on a highly electronegative atom of a different molecule
Hydrolysis
A reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds
Initiation
The first step in radical substitution where radicals are generated by UV radiation
Intermolecular forces
Attractive force between neighbouring molecules: induced dipole/permenant dipole/ hydrogen bonds
Ionic bonding
Electrostatic attraction between oppositely charged ions
First ionisation energy
The energy required to removes one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
Second ionisation energy
The energy required to remove one electron from each ion in one mole of gaseous 1+ ions to from one mole of gaseous 2+ ions
Isotope
Atoms of the same element with a different number of neutrons and different masses
le Chatelier’s principle
When a system in dynamic equilibrium is subjected to a change the, the position of equilibrium will shift to minimise the change
Limting reagent
The substance in a chemical reaction that runs out first
Lone pair
An outer-shell pair of electrons that is not involved in chemical bonding
Metallic bond
The electrostatic attraction between positive metal ions and decolised electrons
Molar volume
The volume per mole of gas, units dm^3 mol^-1, at RTP molar volume is 24 dm^3 mol^-1
Mole
The amount of any substance containing as many particles as there are carbon atoms in 12g of carbon-12
Nucleophile
An atom (or group of atoms) that is attracted to an electron deficient center or atom, where it donates a pair of electrons to form a new covalent bond
Oxidation
Loss of electrons or an increase in oxidation number
Oxidising agent
A reagent that oxidises (takes electons from) another species
Percentage yeild
(Actual mol of product)/ (theoretical mol of product) *100%
Periodicity
A repeating pattern or trend shown across periods
Permenant dipole
A small charge difference across a bond resulting from a difference in electronegativity of bonded atoms
Permanent dipole-dipole force
An attractive force between permenant dipoles in neighbouring polar molecules
Pi - bond
The reactive part of a double bond, formed above and below the plane of the bonded atoms by sideways overlap of p-orbitals
Polar covalent bond
A bond with a permanent dipole
Polar molecule
A molecule with an overall dipole, accounting for dipoles across bonds
Precipitation reaction
The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed
Principal quantum number, n
Number representing the relative overall energy of each orbital, increases with distance from the nucleus, sets of orbitals with the same n value are referred to as energy levels
Propogation
The two repeated step in radical substitution that build up the products in a chain reaction
Redox reaction
A reaction in which both reduction and oxidation take place
Reducing agent
A reagent that reduces (adds electrons to) another species
Reflux
Continual boiling and condensing of a reaction mixture to ensure that the reaction takes place fully between reactants and intermediates
Relative atomic mass, Ar
The weighted mean mass of an atom of an element compared with 1/12 the mass of a carbon 12 atom
Relative formula mass
The weighted mean mass of a formula unit compared with 1/12 the mass of a carbon-12 atom
Relative isotopic mass
The mass of an atom of an isotope compared with 1/12 the mass of a carbon-12 atom
Salt
A chemical compound formed from an acid when a H+ ion from the acid has been replaces by a metal ion of other positive ion
Saturated hydrocarbon
A hydrocarbon with single bonds only
Shell
A group of atomic orbitals with the same principal quantum number
Simple molecular lattice
A 3D structure of molecules, bonded together by weak intermolecular forces
Species
Any type of particle that takes part in a chemical reaction
Specific heat capacity
The energy required to raise the temperature of 1g of a substance by 1*C
Spectator ion
Ions that are present but take no part in a chemical reaction
Standard conditions
A pressure of 100kPa (1 atm), a temp of 298K (25*C), conc of 1 mol dm^-3
Standard solution
A solution of known concentration, standard solutions used in titrations to determine unknown information about another substance
Standard state
The physical state of a substance under standard conditons
Stereoisomers
Compounds with the same structual formula but with a different arrangement of the atoms in space
Stoichiometry
The molar relationship between the relative quantities of substances taking part in a reaction
Stratosphere
The second layer of the Earth’s atmosphere, containing the ‘ozone layer’, 10-50km above Earth
Structural isomers
Molecules with the same molecular formula but with different structural arrangements of atoms
Substitution reaction
A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms
Termination
The end step of radical substitution when two radicals combine to form a molecule
Thermal decomposition
The breaking up of chemical substance with heat into atleast 2 products
Unsaturated hydrocarbon
A hydrocarbon containing carbon to carbon multiple bonds
Van deer Waal’s forces
Very weak attractive forces between induced dipoles in neighbouring molecules (induced dipole)
Volatility
The ease with which a liquid turns into a gas, volatility increases as boiling point decreases
Water of crystallisation
Water molecules that form an essential part of the crystalline structure of a compound
