DEFINITIONS Flashcards
Atomic number (Z)
The number of protons in the nucleus of an atom of that element
Mass number
The sum of the number of protons and the number of neutrons in the nucleus of that atom
Isotope
Atoms of the same element with different masses ( different number of neutrons )
Relative atomic mass (Ar)
The weighted mean/average mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12
Relative isotopic mass
The mass of an individual atom of a particular isotope relative to 1/12 of the mass of an atom of carbon-12
Molecular ion peak
The peak with the highest m/z ratio in the mass spectrum; the M peak
Quantum shell
Defines the energy level of an electron
Orbital
A region within an atom that can hold up to two electrons with opposite spins
Electronic configuration
The number of electrons in each sublevel in each energy level of the atom
Hund’s rule
States that electrons will occupy the orbitals singly before pairing takes place
Pauli Exclusion Principle
States that two electrons cannot occupy the same orbital unless they have opposite spins
First ionisation energy
The energy required to remove an electron from each atom in one mole of atoms in the gaseous state
Second ionisation energy
The energy required to remove an electron from each singly charged positive ion in one mile of positive ions in the gaseous state
Groups
The vertical columns in the Periodic Table
Periods
The horizontal rows in the Periodic Table
Blocks
The Periodic Table is divided into three ; s-block , p-block and d-block
Periodicity
A regular repeating pattern of atomic, physical and chemical properties with increasing atomic number
Delocalised electrons
Electrons that’s are not associated with any single atom or any single covalent bond
Metallic bonding
The electrostatic force of attraction between the nuclei of metal cations and delocalised electrons
Fragmentation
The process is mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion, which will be registered at the detector.
Hydrocarbon
A compound that contains only carbon and hydrogen atoms
Saturated
A compound containing only single bonds
Unsaturated
A compound containing one or more multiple bonds
Multiple bonds
Two or more covalent bonds between two atoms
Displayed formula
Shows every atom and every bond
Structural formula
Shows ( unambiguously ) how the atoms are joined together
Skeletal formula
Shows all the bonds between carbon atoms
Molecular formula
Shows the actual numbers of each atom in the molecule
Empirical formula
Shows the numbers of each atom in the simplest whole number ratio
Functional group
An atom or group of atoms in a molecule thats is responsible for its chemical reactions
Homologous series
A family of compounds with the same functional group which differ in formula by CH2 from the next member
Structural isomers
Compounds with the same molecular formula but with different structural formulae
Stereoisomers
compounds with the same structural formula (and molecular formula) but the atoms or groups arranged differently in three dimensions
Geometric isomers
Compounds containing a C=C bond with atoms or groups attached at different positions
Restricted rotation
When a C=C bond fixes the position of the atoms or groups attached to the C=C atoms
Fractional distillation
The process used to separate a liquid mixture into fractions by boiling and condensing
Cracking
The breakdown of molecules into shorter ones by heating with a catalyst
Reforming
The conversion of straight-chain hydrocarbons into branched chain and cyclic-hydrocarbons
Complete combustion
Means that all the atoms in the fuel are fully oxidised
Incomplete combustion
Means that some of the atoms in the fuel are not fully oxidised
Biofuels
Fuels obtained from living matter that has died recently
Renewable
Sources that can be continuously replaced
Non-renewable
Sources that are not being replenished, except over geological timescales
Biodiesel
A fuel made from vegetable oils obtained from plants
Bioalcohols
Fuels made from plant matter, often using enzymes or bacteria
Substitution reaction
One in which an atom or group is replaced by another atom or group
Mechanism
The sequence of steps in an overall reaction. Each step should what happens to the electrons involved in bond breaking or bond formation.
Homolytic fission
The breaking of a covalent bond where each of the bonding electrons leaves with one species, forming a radical
Radical
A species that contains an unpaired electron
Initiation
Step that involves the formation of radicals, usually as a result of bond breaking caused by ultraviolet radiation
Propagation
The two steps that , when repeated many times over , concert the starting materials into the products of a reaction
Termination
Step that involves the formation of a molecule from 2 radicals
Addition reaction
Reaction in which two molecules combine to form one molecule
Hydrogenation
Involves the addition of hydrogen
Halogenation
Involves the addition of a halogen
Hydration
Involves the addition of water ( or steam )
Diol
Compound containing two OH ( alcohol ) groups
Curly arrows
Represent the movement of electron pairs
Electrophile
A species that is attracted to a region of high electron density
Electrophilic addition
A reaction in which 2 molecules form one molecule and the attacking molecule is an electrophile
Heterolytic fission
The breaking of a covalent bond so that both bonding electrons are taken by one atom
Electron-releasing
A group that pushed electrons toward the atom it is joined to
Monomers
The small molecules that combine together to form a polymer
Repeat unit ( of a polymer )
The set of atoms that are joined together in large numbers to produce the polymer structure
Recycling (polymers)
Converting polymer waste into other materials
Incinerator
Converts polymer waste into energy
Feedstock
Involves converting polymer waste into chemicals that can be used to make new polymers
Biodegradable (polymer)
One that can be broken down by microbes in the environment
Nucleophile
A species that donates a lone pair of electrons to form a covalent bond with and electron-deficient atom
Hydrolysis
A reaction in which water or hydroxide ions replace an atom in a molecule with an —OH group
Nitriles
Organic compounds containing the C-CN group
Primary amines
Compounds containing the C-NH2 group
Nucleophillic substitution
A reaction in which an attacking nucleophile replaces an existing atom or group in a molecule
Ethanolic (solution)
One in which ethanol is the solvent
Elimination (reaction)
One in which a molecule loses atoms attached to adjacent carbon atoms , forming a C=C double bond
Halogenation
A reaction that results in the replacement of the hydroxyl group in an alcohol molecule by a halogen atom
Dehydration (reaction)
Results in the removal of the hydroxyl group in an alcohol molecule , together with a hydrogen atom from an adjacent carbon atom , forming a C=C double bond
Ketones
A homologous series of organic compounds formed by the oxidation of secondary alcohols
Aldehydes
A homologous series of organic compounds formed by the partial oxidation of primary alcohols
Carboxylic acids
A homologous series of organic compounds formed by the complete oxidation of primary alcohols
Heating under reflux
Involves heating a reaction mixture with a condenser fitter vertically
Distillation with addition
Involves heating a reaction mixture , but adding another liquid and distilling off the product as it forms
Simple distillation
Used to separate liquids with very different boiling temperatures
Fractional distillation
Used to separate liquids with very similar boiling temperatures
Solvent extraction
Use to separate a liquid from a mixture by causing it to move from the mixture to the solvent
Molar mass
The mass per mole of a substance. It has the symbol M and the units g mol-1
Mole
The amount of substance that contains the same number of particles as the number of carbon atoms in 12g of the carbon-12 isotope
Avogadro constant
The number of atoms of carbon-12 in exactly 12g of carbon-12
Hydrates
Compounds containing water of crystallisation
Avogadro’s law
States that equal volumes of gases under the same conditions of temperature and pressure contain the same number of molecules
Solute
Substance that is dissolved
Solvent
Substance that dissolves absolute
Solution
Absolute dissolved in a solvent
Mass concentration
The mass (g) of the solute divided by the volume (dm3) of the solution
Molar concentration
The amount (mol) of the solute divided by the volume (dm3) of the solution
Standard solution
A solution whose concentration is accurately known
Primary standards
Substances used to make a standard solution by weighing
Equivalence point
The point at which there are exactly the right amount of substances to complete the reaction
End point
The point at which the indicator just changes colour
Meniscus
The curving of the upper surface in a liquid in a container
Titre
The volume added from the burette during a titration
Concordant titres
Those that are close together (usually within 0.20 cm3 of each other)
Error
The difference between an experimental value and the accepted or correct value
Accuracy
A measure of how close values are to the accepted or correct value
Precision
A measure of how close values are to each other
Random errors
Errors caused by unpredictable variations in conditions
Systematic errors
Errors that are constant or predictable , usually because of the apparatus used
Measurement uncertainty
The potential error involved when using a piece of apparatus to make a measurement
Percentage uncertainty
The actual measurement uncertainty multiplied by 100 and divided by the value recorded
Theoretical yield
The maximum possible mass of a product , assuming complete reaction and no losses
Actual yield
The actual mass obtained
Percentage yield
100 x the actual yield divided by the theoretical yield
Atom economy
The molar mass of the desired product divided by the sun of the molar masses of all the products , expressed as a percentage
Displacement reaction
A reaction in which one element replaces another element in a compound
Precipitation reaction
Reactions in which an insoluble solid is one of this products
Homogeneous system
A system in which all the components are in the same phase
Heterogenous system
A system in which at least two different phases are present
Exothermic
Heat energy is transferred from the system to the surroundings
Endothermic
Heat energy is transferred from the surroundings to the system
Standard enthalpy change of reaction
The enthalpy change measured at 100kPa and a stated temperature, usually 298K, when the number of moles of substances in the equation as written react
Standard enthalpy change of combustion
The enthalpy change measured at 100kPa and at a stated temperature , usually 298K , when one mole of a substance is completely burned in oxygen
Standard enthalpy change of neutralisation
The enthalpy change measured at 100kPa and a stated temperature , usually 298K , when one mole of water is produced by the neutralisation of an acid with an alkali
Standard enthalpy change of formation
The enthalpy change measured at 100kPa and a stated temperature , usually 298K , when one mole of a substance is formed from its elements in their standard states
Hess’s law
The enthalpy change of a reaction is independent of the path taken in converting reactants into products , provided the initial and final conditions are the same in each case
Bond enthalpy
The enthalpy change when one mole of a bond in the gaseous state is broken
Mean bond enthalpy
The enthalpy change when one mole of a bond , averaged out over many different molecules , is broken
Electronegativity
The ability of an atom to attract a bonding pair of electrons in a covalent bond
Polar covalent bond
A type of covalent bond between two atoms where the bonding electrons are unequally distributed. Because of this, one atom carries a slight negative charge and the other a slightly positive charge
