Key Terms Flashcards
Accurate result
A result that’s really close to the true answer
Achiral molecule
A molecule that can be superimposed on its mirror image
Acid anhydride
A molecule formed from 2 identical carboxylic acid molecules, joined via an oxygen atom with the carbonyl groups on either side
Acid dissociation constant (Ka)
An equilibrium constant specific to weak acids that relates the acid concentration to the concentration of [H+] ions
Ka = [H+][A-] / [HA]
Acidic buffer
A buffer with a pH of less than 7 containing a mixture of a weak acid with one of its salts
Acyl chloride
A molecule which contains the functional group COCl
Acylation
When an acyl group (-COR) is added to a molecule
Addition polymer
A type of poly,we firmed by joining small alkenes (monomers) together
Adsorption
The attraction between a substance and the surface of the solid stationary phase in thin-layer chromatography, column chromatography and gas chromatography
Aim
The question an experiment is trying to answer
Alcohol
A substance with the general formula CnH(2n+1)OH
Aldehyde
A substance with the general formula CnH2nO which has a hydrogen and one alkyl group attached to a carbonyl carbon atom
Amide
A carboxylic acid derivative which contains the functional group CONH2
Amide link
The -CONH- group which is found between monomers in a polyamide
Amine
A molecule where one or more of the hydrogen atoms in ammonia have been replaced with an organic functional group, such as an alkyl or an aromatic group
Amino acid
A molecule with an amino group (NH2) and a carboxyl group (COOH)
Amphoteric
Having both acidic and basic properties
Anomalous result
A result that doesn’t fit in with the pattern of the other results in a set of data
Aromatic compounds
A compound that contains a benzene ring
Arrhenius equation
An equation that links the rate constant, k, to temperature and activation energy
Arrhenius plot
A graph where 1/temperature is plotted against ln k, where k is the rate constant
Autocatalysis
When a reaction is catalyses by one of its products
Base (of DNA)
One of 4 molecule: Adenine Thymine Cytosine Guanine They're attached to the sugar-phosphate backbone in DNA
Basic Buffer
A buffer with a pH of more than 7 containing a mixture of a weak base with one of its salts
Bidentate ligand
A ligand that can form 2 co-ordinate bonds in a complex ion
Biodegradable
Will break down naturally
Biodiesel
A mixture of methyl esters of fatty acids which can be used as a carbon neutral fuel
Bond dissociation enthalpy
The enthalpy change when all the bonds of the same type in 1 mole of gaseous molecules are broken down
Born-Haber cycle
An enthalpy change that allows you to calculate the lattice enthalpy change of formation for a system
Brønsted - Lowry acid
A proton donor
Brønsted - Lowry base
A proton acceptor
Buffer
A solution that resists changes in pH when small amounts of acid or alkali are added
Catalyst
A substance that increases the rate of a reaction by providing an alternative reaction pathway with a lower activation energy. The catalyst is chemically unchanged at the end of the reaction.
Catalyst poisoning
When impurities in a reaction mixture bind to a catalyst’s surface, blocking reactants from being absorbed and reducing the effectiveness of the catalyst
Catalytic Hydrogenation
A chemical reaction in which hydrogen is added to an unsaturated molecule by reacting the molecule with molecular hydrogen (H2) in the presence of a catalyst.
Categoric data
Data that can be sorted into categories
Cationic surfactant
A surfactant which is positively charged.
Casual link
The relationship between 2 variables where a change in one variable causes a change in the other
Cell potential (Ecell)
The voltage between 2 half-cells in an electrochemical cell
Chelate effect
When monodentate ligands are substituted with multidentate ligands, the number of particles and the entropy of the system increases without enthalpy changing significantly. Reactions that result in an increase in entropy are most likely to occur, so multidentate ligands form much more stable complexes than monodentate ligands
Chemical shift
Nuclei in different environments absorb energy of different frequencies. NMR spectroscopy measures these differences relative to a standard substance - the difference is called the chemical shift (δ)
Chiral carbon
A carbon atom that has 4 different groups attached to it
Chromatogram
A visual record (such as a pattern of spots or a graph) of the results of a chromatography experiment
Chromatography
An analytic technique which uses a mobile phase and a stationary phase to separate out mixtures into their constituent components
Cisplatin
A platinum-containing complex ion with a square planar shape that can be used as an anti-cancer drug
Cis-trans isomerism
A special type of E/Z isomerism where 2 of the groups attached to the carbon atoms around the C=C double bond are the same
Clock reaction
A reaction where, after a period of time, there’s a sudden increase in the concentration of a product
Colorimeter
An instrument for measuring how much light is absorbed by a sample
Column chromatography
A type of chromatography where the stationary phase is a column packed with a solid, and the mobile phase is a liquid solvent
Complex ion
A metal ion surrounded by co-ordinatley bonded ligands
Condensation polymer
A type of polymer formed through a series of condensation reactions
Condensation reaction
A chemical reaction in which 2 molecules are joined together and a small molecule is eliminated
Contact Process
An industrially used method of producing sulfuric acid
Continuous data
Data that can have any value on a scale
Continuous monitoring
A method of following a reaction by monitoring the formations of a product or the loss of a reactant, over the course of a reaction
Control variable
A variable that is kept constant in an experiment
Co-ordinate bond
A covalent bond in which both electrons in the shared pair come from the same atom (also called a dative covalent bond)
Co-ordinate number
The number of co-ordinate bonds that are formed with the central metal ion in a complex ion
Correlation
The relationship between 2 variables
Corrosive substance
A substance that may cause chemical burns
d-block
The block of elements in the middle of the periodic table
d sub-level
A type of sub-level. Each can hold 10 electrons
Data Logger
A device that can record data readings automatically at set intervals and store them to be looked at later
Dative Covalent bond
A covalent bond in which both electrons in the shared pair come from the same atom (also called a co-ordinate bond)
Dependent variable
The variable that you measure in an experiment
Deuterated solvent
A solvent which has had all of its hydrogen atoms exchanged for deuterium atoms
Deuterium
An isotope of hydrogen. It contains one neutron, one proton and one electron
Diprotic acid
An acid that releases 2 H+ ions per molecule
Discrete data
Data that can only take certain values
Distillation
A method of separating liquids with different boiling points by generally heating them
Disulfide bond
A covalent bond between sulfur atoms in 2 different thiol groups
DNA
Deoxyribonucleic acid - 2 complementary polynucleotide chains joined together in a double helix structure
Double helix
A shape formed by 2 helices twisted around each other
Drying agent
An anhydrous salt, such as magnesium sulfate or calcium chloride, that can be used to remove water from an organic product
E/Z isomerism
A type of stereoisomerism that is caused by the restricted rotation about a C=C double bond. Each of the carbon atoms must have 2 different groups attached
Electric heater
A piece of equipment used to heat a reaction mixture, consisting of a plate of metal that is heated to a set temperature
Electrochemical cell
An electrical circuit made from 2 metal electrodes dipped in salt solutions and connected by a wire
Electrochemical series
A list of electrode potentials written in order from most negative to most positive
Electrode potential
The voltage measured when a half-cell is connected to a standard hydrogen electrode
Electromotive force (EMF)
Another name for cell potential
Electrophile
An electron deficient (and usually positively charge)species which is attracted to regions of high electron density
Electrophilic substitution
A reactions mechanism where an electrophile substitutes for an atom (or group of atoms) in a molecule
Enantiomer
A molecule that has the same structural formula as another molecule but with 4 groups arranged around a chiral carbon atom so that it is a non-superimposable mirror image of the other molecule
End point
The point in a titration at which all the acid is just neutralized and the pH curve becomes vertical
Endothermic reactions
A reaction that absorbs energy (ΔH is positive)
Energy gap (ΔE)
The amount of energy needed for an electron to transfer to a higher orbital
Enthalpy change of atomistion of a compound (ΔHat)
The enthalpy change when 1 mole of a compound in its standard states is converted to gaseous atoms
Enthalpy change of atomisation of an element (ΔHat)
The enthalpy change when 1 mole of gaseous atoms is formed from an element in its standard states
Enthalpy change of formation (ΔH f)
The enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions
Enthalpy change of hydration (ΔHhyd)
The enthalpy change when 1 mole of aqueous ions is formed from gaseous ions
Enthalpy change of solution (ΔH sol)
The enthalpy change when 1 mole of an ionic substance dissolves in enough solvent to form an infinitely dilute solution
Entropy (S)
A measure of the amount of disorder in a system (e.g. the number of ways the particles can be arranged and the number of ways that the energy can be shared out between the particles)
Enzyme
A protein that acts as a biological catalyst
Equilibrium constant
Kp
A ratio worked out from the partial pressures of the gaseous products and reactants once a reversible reaction has reached equilibrium
Ester
A molecule that contains the functional group RCOOR
Ester link
The -COO- group which is found between monomers in a polyester
Esterification
Forming an ester by heating a carboxylic acid and an alcohol in the presence of a strong acid catalyst
Exothermic reaction
A reaction that gives out energy (ΔH is negative)
Fatty acid
A long chain carboxylic acid which can combine with glycerol to form a fat or an oil
Feasible reaction
A reaction that, once started, will carry on to completion, without any energy being supplied to it
Fehling’s solution
A blue solution of complexed coppe(II) ions dissolved in sodium hydroxide which can be used to distinguish between aldehydes and ketones
Filtration
A technique used to separate solids from liquids
First electron affinity
The enthalpy change when 1 mole of gaseous 1- ions is made from 1 mole of gaseous atoms
First ionisation energy
The enthalpy change when 1 mole of gaseous 1+ ions is formed from 1 mole of gaseous atoms
Flammable substance
A substance that catches fire easily
Free-energy change
A measure which links enthalpy and entropy changes to predict whether a reaction is feasible
Fehling’s solution
A blue solution of complexed coppe(II) ions dissolved in sodium hydroxide which can be used to distinguish between aldehydes and ketones
Filtration
A technique used to separate solids from liquids
First electron affinity
The enthalpy change when 1 mole of gaseous 1- ions is made from 1 mole of gaseous atoms
First ionisation energy
The enthalpy change when 1 mole of gaseous 1+ ions is formed from 1 mole of gaseous atoms
Flammable substance
A substance that catches fire easily
Free-energy change
A measure which links enthalpy and entropy changes to predict whether a reaction is feasible
Fehling’s solution
A blue solution of complexed coppe(II) ions dissolved in sodium hydroxide which can be used to distinguish between aldehydes and ketones
Filtration
A technique used to separate solids from liquids
First electron affinity
The enthalpy change when 1 mole of gaseous 1- ions is made from 1 mole of gaseous atoms
First ionisation energy
The enthalpy change when 1 mole of gaseous 1+ ions is formed from 1 mole of gaseous atoms
Flammable substance
A substance that catches fire easily
Free-energy change
A measure which links enthalpy and entropy changes to predict whether a reaction is feasible
ΔG = ΔH - TΔS
Fuel cell
A device that converts the energy of a fuel into electricity through an oxidation reaction
Gas chromatography (GC)
A type of chromatography where the stationary phase is a tube packed with a solid, and the mobile phase is an unreactive gas
Haber process
An industrially used method of producing ammonia
Haem
A part of the haemoglobin molecule, consisting of a central Fe(II) ion bonded to 4 nitrogen atoms from a porphyrin ring
Haemoglobin
A protein found in blood that helps to transport oxygen around the body
Half-cell
One half of an electrochemical cell
Half-equation
An ionic equation that shows oxidation or reduction - one half of a full redox equation
Halogen carrier
A molecule which can accept a halogen atom (eg AlCl3)
Used as a catalyst in Friedel-Crafts acylation reactions
Hess’s law
The total enthalpy change of a reaction is always the same, no matter of the route taken
Heterogeneous catalyst
A catalyst which is in a different physics state to the reactants
Homogeneous catalyst
A catalyst which is in the same physical state as the reactants
Hydrogen bonding
A type of weak bonding which occurs between hydrogen atoms and electronegative atoms in polar groups (eg -NH2 and -OH)
Hydrolysis
A reaction where molecules are split apart by water molecules
Hydroxynitrile
A molecule which contains a hydroxyl group (OH) and a nitrile group (CN)
Hypothesis
A suggested explanation for a fact or observation
Independent variable
The variable that you change in an experiment
Indicatior
A substance that changes colour over a particular pH range
Inhibitor
A molecule that is a similar shale to a substrate of an enzyme, that blocks the active site of the enzyme and stops it interacting with the substrate
Initial rates method
An experimental technique that can be used to work out the orders of a reaction
Integration trace
A line on a H1 NMR spectrum that has a change in height that is proportional to the area of the peak its next to
Ionic product of water
Kw
A constant generated by multiplying the Kc for the dissociation of water by [H2O]
Kw = [H+] [OH-]
Irritant substance
A substance that may cause inflammation or discomfort
Isoelectric point
The pH at which the average overall charge on a molecule is zero
Ketone
A substance with the general formula CnH2nO which has 2 alkyl groups attached to a carbonyl carbon atom
Lattice dissociation enthalpy
The enthalpy change when 1 mole of a solid ionic compound is completely dissociated into its gaseous ions
Lattice formation enthalpy
The enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions
Le Chatelier’s Principle
If there’s a change in concentration pressure or temperature, an equilibrium will move to help counteract the change
Ligand
An atom, ion or molecule that donates a pair of electrons to a central metal ion in a complex ion
Ligand substitution/ exchange reaction
A reaction where one or more ligands are changed for one or more other ligands in a metal complex ion
Melting point apparatus
Equipment that can be used to test the purity of an organic product by measuring it’s melting point
Metal-aqua complex ion
A species formed when metal ions dissolved in water. The water molecules from co-ordinate bonds with the metal ions
Method
A set of instructions detailing how to carry out an experiment safety
Methyl orange
A pH indicator that changes colour between pH 3.1 and 4.4
Mobile phase
A liquid or a gas used in chromatography which contains molecules that can move
Mole fraction
A measure of the proportion of a mixture that is made up of a particular substance
Monodentate ligand
A ligand that can only form one co-ordinate bond in a complex ion
Monomer
A small molecule which can join together with other monomers to form a polymer
Monoprotic acid
An acid that releases one H+ ion per molecule
Multidentate ligand
A ligand that can form 2 or more co-ordinate bonds in a complex ion
Multiplet
A split peak on a H1 NMR Spectrum
Doublet, triplet, quartet
n+1 rule
Peaks on a H1 NMR spectrum always split into the number of hydrogens on the neighbouring carbon(s), plus one
N-substituted Amide
An Amide where one if the hydrogens attached to the nitrogen has been substituted with an alkyl group
Nitration
A reaction in which a nitro group (NO2) is added to a molecule
Nuclear magnetic resonance (NMR) spectroscopy
An analytic technique used to determine the relative environment of the nuclei in a compound
Nucleophile
A species that forms a bond with an electrophile by donating a pair of electrons
Nucleophilic addition-elimination
A reaction mechanism where a nucleophiles adds on to the δ+ carbon atom of a carbonyl group and another molecule is eliminated
Nucleophilic substitution
A reaction mechanism where a nucleophiles substitutes for an atom (or group of atoms) in a molecule
Nucleotide
A molecule that is made up of a phosphate ion, a pentose sugar, and a (genetic) base
Optical isomer
A molecule that has the same structural formula as another molecule but with 4 groups arranged around a chiral carbon atom so that it is a non-superimposable mirror image of the other molecule
Orbital
A region of a sub-level that contains a maximum of 2 electron
Order of reaction (reaction order)
A number that tells you how the concentration of a particular reactant affects the reaction rate
Ordered (ordinal) data
Categoric data where the categories can be put in order
Oxidation
The loss of electrons
Oxidation state
The total number of electrons an element has donated or accepted, also called the oxidation number
Oxidising agent
Something that accepts electrons and gets reduced
Oxidising substance
A substance that reacts to form oxygen, meaning that other substances burn more easily in its presence
Partial pressure
The pressure that an individual gas, in a mixture of gases, exerts on a system
Pentose sugar
A sugar with 5 carbon atoms
Peptide
A polymer formed from reactions between amino acids
Peptide link (bond)
The bonds which hold amino acids together in a protein
pH
A measure of the hydrogen ion concentration in a solution
pH= -log[H+]
pH chart
A chart that shows the colour of an indication at different pHs
pH curve
A graph of pH against volume of acid/alkali added
pH meter
An electronic device used to measure pH, made up of a probe connected to a digital display
Phenolphthalein
A pH indicator that changes colour between 8.3 and 10
Plane polarised light
Light in which all the waves are vibrating in the same plane
Polyamide
A polymer containing Amide links between monomers. Can be formed from reactions between dicarboxylic acids and diamines
Polyester
A polymer containing ester links between the monomers. Can be formed from reactions between dicarboxylic acids and diols
Polymer
A long molecule formed from lots of repeating units (called monomers)
Polynucleotide
A polymer formed of nucleotides
Polypeptide
A polymer formed from reactions between amino acids
Porphyrin
A multidentate ligand found in a number of biological molecules including haemoglobin
Precise result
Results where the data have a very small spread around the mean
Prediction
A specific testable statement about what will happen in an experiment, based on observation, experience or a hypothesis
Primary structure (of proteins)
The first ‘level’ that describes the structure of protein - ie the sequence of amino acids in the polypeptide chain
Protein
One or more polypeptides folded into a structure which has a biological function
Purely ionic model of a lattice
A model which assumes that all the ions in a lattice are spherical and have their charge evenly distributed around them. This model is also known as the perfect ionic model
Racemate (or racemic mixture)
A mixture that contains equal quantities of each enantiomer of an optically active compound
Random error
An error introduced by a factor that you cannot control
Rate constant
K
A constant in the rate equation for a reaction at a certain temperature. The larger it is the faster the rate of reaction.
Rate-determining step
The slowest step in a reaction mechanism which determines the overall rate of a reaction
Rate equation
An equation of the form rate = k[A]^m [B]^n which tells you how the rate of a reaction is affected by the concentration of reactants
Reaction rate
The change in the amount of reactants or products over time
Recrystallisation
A process of purifying a solid organic compound
Redistillation
A process of purification, by repeatedly distilling
Redox potential
A measure of how easily an atom, molecule or ion is reduced
Redox reaction
A reaction where reduction and oxidation happens simultaneously
Redox titration
A titration which can be performed
Reducing agent
Something that donates electrons and gets oxidised
Reduction
The gain of electrons
Refluxing
A method of heating a reaction so that you can increase the temperature of an organic reaction to boiling without losing volatile solvents, reactants or products. Any vaporised compounds are cooled, condense and drip back into the reaction mixture
Repeatable result
A result is repeatable if you can repeat an experiment multiple times and get the same result
Repeating unit
A part of a polymer that repeats over and over again
Reproducible result
A result is reproducible if someone else can recreate your experiment and get the same result you do
Retention
The process of being absorbed onto the stationary phase in chromatography
Retention time
The time taken for a component of a mixture to pass through a chromatography column to the detector at the other end
Rf value
The ratio of the distance travelled by a spot to the distance travelled by the solvent in thin layer chromatography
Risk assessment
A procedure carried out to identify any hazards associated with an experiment and how to reduce the risks these hazards present
Salt bridge
A connection between 2 half-cells that ions can flow through, used to complete the circuit. Usually a piece of filter paper soaked in a salt solution or glass tube filled with a salt solution
Sand bath
A piece of equipment used to heat a reaction mixture, consisting of a container filled with sand that can be heated to a set temperature
Saturated fatty acid
A fatty acid that contains no double bonds - found in fats
Second electron affinity
The enthalpy change when 1 mole of gaseous 2- ions is made from 1 mole of gaseous 1- ions
Second ionisation energy
The enthalpy change when 1 mole of gaseous 2+ ions is formed from 1 mole of gaseous 1+ ions
Secondary structure of proteins
The second ‘level’ that describes the structure of protein
(Eg how the primary structure folds and twists to form a a-helix or b-pleated sheet, held together by hydrogen bonds
Separation
A technique to separate the water-soluble impurities out of an organic mixture. The aqueous and organic solutions can be separated as they are immiscible, and separate out into 2 distinct layers due to their different densities
Solvent extractions
A form of separation, where the product is shaken vigorously with an immiscible solvent
Solvent front
The distance travelled by the solvent in thin-layer chromatography
Spectroscopy
The study of what happens when radiation interacts with matter
Splitting patterns
Peaks in 1H NMR spectra may be split into further peaks. The resultant group of peaks is called a splitting pattern
Standard conditions
298K (25°C)
100 kPa
All ion concentrations of 1.00 Moldm-3
Standard electrode potential
The voltage measured under standard conditions when a half-cell is connected to a standard hydrogen electrode
Standard hydrogen electrode
An electrode where hydrogen gas is bubbled through a solution of aqueous H+ ions under standard conditions
Stationary phase
A solid, or a liquid held in a solid, used in chromatography which contains molecules that can’t move
Stereoisomer
A molecule that has the same structural formula as another molecule but with the atoms arranged differently in space
Stereoisomer
A molecule that has the same structural formula as another molecule but with the atoms arranged differently in space
Stereospecific active site
An active site that only reacts with one enantiomer of a chiral compound
Strong acid/base
An acid or base that fully dissociates in water
Sub-level
A subdivision of an energy level
S,p.d.f
Substrate
A molecule that is acted on by an enzyme
Surfactant
A compound which is partly soluble and partly insoluble in water
Synthetic route
A method detailing how to create a chemical
Systematic error
An error introduced by the apparatus or method you use in an experiment
Tertiary structure of proteins
The 3rd level that describes the structure of protein
ie how the secondary structure folds and twists to form a 3D molecule, held together by hydrogen and disulphide bonds
Thin layer chromatography
A type of chromatography where the stationary phase is a plate coated with a solid and the mobile phase is a liquid solvent
Titration
An experimental technique that lets you work out exactly how much alkali is needed to neutralise a quantity of acid
Tollens’ reagent
A colourless solution of silver nitrate dissolved in aqueous ammonia which can be used distinguish between aldehydes and ketones
Toxic substance
A substance that can cause illness or even death
Transition metal
A metal that can form one or more stable ions with a partially filled d sub level
Unsaturated fatty acid
A fatty acid that contains double bonds - found in oils
Valid result
A result which answers the question it was intended to answer
Variable
A factor in an experiment or investigation that can change or be changed
Washing
A method of purifying a product by washing it with chemicals, such as washing with sodium hydrogen carbonate solutions to remove acids
Water bath
A piece of equipment used to heat a reaction mixture, consisting of a container filled with water that can be heated to s set temp
Weak acid / base
An acid or base that only partially dissociates in water
Zwitterion
A dipolar ion which has both a negative and positive charge in different parts of the molecule
