A2 Level Chemistry Terminology

Acid Dissociation Constant Ka
the acid dissociation constant of an acid (HA) - Ka = [H+(aq)][A-(aq)]/[HA(aq)] - Ka = 10^-pKa - pKa = -log (Ka)
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Activation Energy
the minimum energy required to start a reaction by breaking bonds in the reactants
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Addition Polymer
a very long molecular chain formed by repeated addition reactions of many unsaturated (C=C) alkene molecules (monomers)
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Addition Reaction
a reaction in which a reactant is added to an unsaturated (C=C) molecule to make a saturated molecule
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Aliphatic Hydrocarbon
a hydrocarbon where carbon atoms are joined together in straight or branched chains
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a base that dissolves in water forming OH- (aq) ions
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the homologous series of organic chemical compounds with the general formula CnH2n+2
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Alkylammonium Salt
a compound where the hydrogen(s) on an ammonium ion have been substituted by alkyl chains
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addition of hydrocarbon chains to an organic compound
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Alkyl Group
an alkane with a hydrogen atom removed, e.g. -CH3, C2H5 - R group
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a class of compound with a functional group made of an acyl group, which is directly attached to an amine - NH2
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Amount of Substance
the quanity whose unit is the mole - counting atoms
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Amphoteric Chemicals
chemicals that can reacts with both acids and bases
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a negatively charged ion
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a substance that contains no water molecules
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Arrhenius Plot
a graph of ln K = ln A - Ea/RT - ln K against 1/T
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Atomic Orbital
a region of space where it is likely that you will find electrons - each orbital can hold up to two electrons, with opposite spin
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Atomic (Proton) Number
the number of protons in the nucleus of an atom
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Average Bond Enthalpy
the mean energy needed for 1 mole of a given type of gaseous bonds to undergo homolytic fission
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Avogadro Constant
the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol^-1)
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a chemical that will react with an acid
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a naturally occuring aromatic compound, which is a very stable planar ring structure with delocalised electrons
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Benzene Derirative
a benzene ring that has undergone a substitution reaction
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Boltzmann Distribution
the distribution of energies of molecules at a particular temperature, often shown as a graph
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Bronsted-Lowry Acid
a proton (H+) donor
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Bronsted-Lowry Base
a proton (H+) acceptor
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Buffer Solution
a mixture that minimises pH changes on addition of small amounts of acid or base
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an organic ion in which a carbon atom has a position charge
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a substance that increases the rate of reaction without being used up in the process
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a positively charge ion
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Chemical Shift
the scale that compares the frequency of NMR absorption with the frequency of the reference peak of TMS
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Chiral Carbon
a chrial carbon has four different groups attached to it
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a visible record showing the result of separation of the components of a mixture by chromatography
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Cis-Trans Isomerism
a type of E/Z isomerism where each carbon of the double C=C bond carries the same atom or group
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Complex Ion
a transition metal ion bonded to one or more ligands by coordinate bonds/dative covalent bonds
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Condensation Polymerisation
the chemical reaction to form a long chain molecule by elimination of a small molecule, e.g. water
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Conjugate Acid-Base Pair
two species that transform into each other by gain or loss of a proton (H+)
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Coordinate Bond/Dative Covalent Bond
a bond formed by a shared pair of electrons that has been provided by one of the bonding atoms only
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Coordination Number
the total number of coordinate (dative covalent) bonds formed between a central metal ion and its ligands
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Covalent Bond
a bond formed by a shared pair of electrons between nuclei
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Curly Arrow
a symbol used in reaction mechanisms to show the movement of an electron pair
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Degradable Polymer
a polymer that breaks down into smaller fragments when exposed to light, heat or moisture
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Delocalised Electrons (e-)
electrons that are shared between more than two atoms, e.g. metallic bonding
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an isotope of hydrogen and does not produce a signal in the proton (H+) NMR spectrum
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Directing Effect
how a functional group attached directly to an aromatic ring affect which carbon atoms are more likely to undergo substitution
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Displayed Formula
a formula which shows the relative positions of atoms and the bonds between them
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the oxidation and reduction of the same element in a redox reaction
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a technique used to separate miscible liquids or solutions
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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 and all the chemical have their concentrations maintained
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Electron Structure/Configuration
the arrangement of electrons in an atom or ion
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an electron pair acceptor
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Electrophilic Substitution
a substitution reaction where an electrophile is attracted to an electron rich atom or part of a molecule and a new covalent bond is formed by the electrophile accepting an electron pair
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Elimination Reaction
an organic chemical reaction in which one reaction forms two products - small molecule, e.g. water, is released
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Empirical Formula
the simplest whole number ratio of atoms of each element present in a compound
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an optical isomer
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a reaction in which the enthalpy of the products is greater than the enthalpy of the reactants - heat taken in from surroundings (+) (up)
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End Point
the point in titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator - colour at end point is midway between colours of acid and conjugate base forms
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Enthalpy Cycle
a pictorial presentation showing alternative routes between reactants and products
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Enthalpy Profile Diagram
a diagram of a reaction that allows you to compare the enthalpy of the reactants with the enthalpy of the products
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Enthalpy (H)
the heat content that is stored in a chemical system
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Entropy (S)
the quantitative measure of the degree of disorder in a system
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Equilibrium Law
Kc =[products]/[reactants] *remember number in front is placed as a power
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Equivalence Point
the point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution = stochiometry of the reaction
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Equivalent Carbon Atoms
carbon atoms bonded to the same atom - experience same magnetic field in the NMR spectrometer
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Equivalent Protons
hydrogen atoms bonded to the same atoms - experience same magnetic field in the NMR spectrometer
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the chemical reaction which forms an ester
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a reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants - heat loss to the surroundins (-) (down)
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E/Z Isomerism
a type of stereoisomerism that is caused by the restricted rotation around the double C=C bond - two different groups are attached to each carbon atom
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First Electron Affinity
the enthalpy change accompanying the formation of 1 mole of gaseous 1- ions from gaseous atoms
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First Ionisation Energy
the energy change that accompanies the removal of 1 mole of electrons from 1 mole of gaseous atoms
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Free Energy Change (Gibbs)
the balance between enthalpy, entropy and temperature for a process - change in G = change in enthalpy (H) - ((Temperature (K) x (change in entropy (S)) - process is spontaneous when change in G = negative
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Friedel-Crafts Reaction
a substitution reaction where hydrogen is exchanged for an alkyl or acyl chain - allow electrophilic substitution to occur on an aromatic ring
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Functional Group
a group of atoms that is responsible for the characteristic chemical reactions of a compound
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General Formula
the simplest algebraic formula for a homologous series
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Geometric Isomers
molecules that have the same structural formula but a different arrangement in space
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Giant Covalent Lattice
a 3D structure of atoms that are all bonded together by strong covalent bonds
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Giant Ionic Lattice
a 3D structure of oppositely charged ions, held together by strong electrostatic forces of attraction - ionic bonds
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Giant Metallic Lattice
a 3D structure of positive metal ions (cations) and delocalised electrons bonded together by strong metallic bonds
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a column in the periodic table - similar chemical properties - same number of outer shell electrons
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the time taken for the concentration of a reactant to reduce by half
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Hess' Law
states that the enthalpy change in a chemical reaction is independent of the route it takes
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Heterogenous Equilibrium
an equilibrium in which species making up the reactants and products are in different physical states
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Homogenous Equilibrium
an equilibrium in which all the species making up the reactants and products are in the same physical state
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Homologous Series
a series of organic compounds that have the same functional group with successive members differing by -CH2
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a chemical reaction where water is a reactant in a decomposition reaction
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a species formed in one step of a multi-step reaction that is used up in a subsequent step, and is not seen as either a reactant or a product of the overall equation
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a positively or negatively charged ion or (covalently bonded) group of atoms (molecular ion)
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Ionic Bonding
the electrostatic attraction between oppositely charged ions
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Ionic Product of Water - Kw
Kw = [H+(aq)][OH-(aq)] - 25 degrees celsius - Kw = 1x10^-14 mol^2 dm^-6
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Isoelectric Point
the pH value at which the amino acid exists as a zwitterion
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Lattice Enthalpy (LE)
the enthalpy change that accompanies the formation of one mole of an ionic lattice from its gaseous ions under standard conditions
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Le Chatelier's Principle
states that when a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change
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Lewis Acid
an electron pair acceptor
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a molecule or ion that can donate a pair of electrons to the transition metal ion to form a coordinate bond
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Ligand Substitution
a reaction in which one ligand in a complex ion is replaced by another ligand
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Lone Pair
an outer-shell pair of electrons that is not involved in chemical bonding
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Mass (nucleon) Number
the number of particles (protons and neutrons) in the nucleus of an atom
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Mobile Phase
the phase that moves in chromatography, e.g. solvent
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a simplified version that allows us to makes predictions and understand observations more easily
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Molar Mass (M)
the mass per mole of a substance - gmol^-1
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the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope
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Mole Fraction
a measure of how much of a given substance is present in a reaction mixture (%)
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Molecular Formula
shows the numbers and type of the atoms of each element in a compound
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Molecular Ion - M+
the positive ion formed in mass spectrometry when a molecule loses an electron - M+ ion peak = Mr of compound
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small molecules that are used to make polymers
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a chemical reaction in which an acid and a base react together to produce a salt and water
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an organic chemical with a -CN functional group
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a species that contains a lone pair of electrons of a negative charge and is attracted to positive areas of a molecule - donates a pair of electrons
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Optical Isomers
molecules which are non-superimposable mirror images of each other - same chemical properties - interact with polarised light differently
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with respect to a reactant, the order is the power to which the concentration of the reactant is raised in the rate equation
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Overall Order
the overall order of a reaction is the sum of the individual orders, m + n
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loss of electrons - increase in oxidation number
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Oxidation Number
a measure of the number of electrons that an atom uses to bond with atoms of another element - rules
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Oxidising Agent
the species that is reduced in a reaction and causes another species to be oxidised [O] - e.g. potassium dichromate
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Partial Pressure
the pressure an individual gaseous substance would exert if it occupied a whole reaction vessel on its own
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a physically distinctive form of a substance - solid, liquid or gas
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a class of aromatic compounds where a hydroxyl group is directly attached to the aromatic ring
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-log[H+(aq)] / [H+(aq)] = 10^-pH
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Pi Bond
sideways overlap of adjacent p-orbitals above and below the bonding carbon atoms
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Polar Molecule
a molecule with an overall dipole, having taken into account any dipoles across bonds
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a large complex macromolecule made from small repeating units - monomers
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Precipitation Reaction
the formation of a solid from a solution during a chemical reaction - two aqueous solutions mixed together
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Qualitative Analysis
an observable change and does not involve observations using numerical values, e.g. colour change - bias - unreliable
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Rate Constant - K
the constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
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Rate-Determining Step
the slowest step in the reaction mechanism of a multi-step reaction
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Rate Equation
rate = k[A]^m[B]^n - powers = orders with respect to the reactants
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Rate of Reaction
the change in concentration of a reactant or a product per unit time
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Reaction Mechanism
a series of steps that, together, make up the overall reaction; a model with steps to explain and predict a chemical reaction
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a method for purifying organic compounds
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Redox Reaction
a reaction in which both reduction and oxidation take place
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Reducing Agent
the species that is oxidised in a reaction and causes another species to be reduced - [H] - e.g. H2SO4, NH4
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gain of electrons or decrease in oxidation number
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a technique used to stop reactions mixtures boiling dry - gases don't escape - condense back into liquids
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Relative Molecular Mass
the weighted mean mass of a molecule of a compound compared with 1/12 of the mass of an atom of carbon-12
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Repeat Unit
the arrangement of atoms that occurs many times in a polymer - structure of a monomer - [ ]n
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Retention Time
the time taken for a component to travel from the inlet to the detector in a gas chromatograph
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where the synthetic route is designed by looking at the target molecule and working backwards
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Rf Value
a comparison between how far a component has moved compared to the solvent in thin layer chromatography
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any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion - metal ion or ammonium ion NH4+
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Saturated Hydrocarbon
a hydrocarbon chain with single C-C bonds only
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Second Electron Affinity
the enthalpy change accompanying the formation of 1 mole of gaseous 2- ions from 1 mole of gaseous 1- ions
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Second Ionisation Energy
the energy change that accompanies the formation of 1 mole of gaseous 2+ ions from 1 mole of gaseous 1+ ions
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a group of atomic orbitals with the same principal quantum number - n - energy level
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Skeletal Formula
a simplified structural formula drawn by removing hydrogen atoms from alkyl chains
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Spectator Ions
ions that are present but that play no part in a chemical reaction - not shown in ionic equations
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Spin-Spin Coupling
the interaction between spin states of non-equivalent nuclei that results in a group of peaks in an NMR spectrum
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Standard Conditions
standards set for experimental measurements to allow comparisons to be made between different sets of data - 100kPa and 298K (25 degrees celsius)
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Standard Electrode Potential of a Half Cell (E)
the e.m.f of a half cell compared with a standard hydrogen half-cell, measured at 298K with solution concentrations of 1mol dm^-3 and a gas pressure of 100kPa
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Standard Enthalpy Change of Atomisation (at)
the enthalpy change that accompanies the formaiton of 1 mole of gaseous atoms from the elements in standard states
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Standard Enthalpy Change of Formation (f)
the enthalpy change that accompanies the formation of 1 mole of a compound from its elements
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Standard Enthalpy Change of Hydration (hyd)
the enthalpy change that takes place when dissolving 1 mole of gaseous ions in water
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Standard Enthalpy Change of Solution (sol)
the enthalpy change that takes place when one mole of solute is completely dissolved in water under standard conditions
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Standard Entropy - S
the entropy content of one mole of a substance under standard conditions
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Standard Entropy Change of Reaction (S)
the entropy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states
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Stationary Phase
the phase that does not move in chromatography, e.g. paper
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the longest carbon chain present in an organic molecule
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species with the same structural formula but with a different arrangement of atoms in space
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the molar relationship between the relative quantities of substances taking part in a reaction
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Strong Acid
an acid that completely dissociates in solution
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Structural Formula
provides the minimum detail to show the arrangment of atoms in a molecule
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Structural Isomers
compounds with the same molecular formula but different structural formula
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a group of the same type of atomic orbitals (s,p,d,f) within a shell - s = 2 electrons / p = 6 electrons / d = 10 electrons / f = 14 electrons
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Substitution Reaction
when an atom or group of atoms is replaced by a different atom or group of atoms
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Synthetic Route/Pathway
a series of reactions that can be used to change a starting chemical into a target molecule
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an internal standard for both carbon-13 and proton (H+) NMR spectroscopy
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Transition Element/Metal
a d-block element that has an incomplete d-sub-shell as a stable ion
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Unsaturated Hydrocarbon
a hydrocarbon chain with containing multiple carbon-to-carbon bonds, e.g. double or triple carbon bonds
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Van der Waals' Forces
a type of intermolecular bonding that includes permanent dipole-dipole bonding and induced dipole-dipole interactions (London forces)
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Water of Crystallisation
water molecules that form an essential part of the crystalline structure of a compound
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Weak Acid
an acid that partially dissociates in solution
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an internal salt, with no charge, formed by the donation of a proton (H+) from a carboxylic acid functional group to the amine functional group (-NH2) in an amino acid
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Other cards in this set

Card 2


the minimum energy required to start a reaction by breaking bonds in the reactants


Activation Energy

Card 3


a very long molecular chain formed by repeated addition reactions of many unsaturated (C=C) alkene molecules (monomers)


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Card 4


a reaction in which a reactant is added to an unsaturated (C=C) molecule to make a saturated molecule


Preview of the back of card 4

Card 5


a hydrocarbon where carbon atoms are joined together in straight or branched chains


Preview of the back of card 5
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