Definitions Flashcards
acid
a species that releases H+ ions in aqueous solutions
activation energy
the minimum energy required for a reaction to take place by the breaking of bonds
actual yield
the amount of product obtained from a reaction
addition polymerisation
formation of a very long molecular chain (an addition polymer) by the repeated addition of many unsaturated alkene molecules (monomers)
addition reaction
a reaction in which a reactant is added to an unsaturated molecule to make one saturated molecule
adsorption
the process that occurs when a gas or a liquid or a solute is weakly bonded and held to the surface of a SOLID
alicyclic
an aliphatic compound with the carbon atoms arranged in a non-aromatic ring, with or without side chains
aliphatic
a compound containing carbon and hydrogen atoms joined together in straight/unbranched, branched chains or non aromatic rings
aromatic
some or all of the carbon atoms are found in a benzene ring
alkali
a base that dissolves in water and aqueous solutions to release hydroxide ions OH-
alkanes
the hydrocarbon homologous series with the general formula CnH2n+2, saturated, with only single bonds, sigma bonds
alkenes
the hydrocarbon homologous series with the general formula CnH2n, unsaturated with a carbon-carbon double bond, compromising a pi and sigma bond
alkyl group
a SIDE chain formed by removing a hydrogen atom from an ALKANE parent chain, shown by R, and usually have the general formula CnH2n+1
amount of substance
the quantity whose unit is the mole. Chemists use this as a means of counting particles
anhydrous
containing no water molecules
anion
a negatively charged ion with MORE ELECTRONS THAN PROTONS
atom economy
measure of how well atoms have been utilised in a chemical reaction: sum of molar masses of desired products/ sum of molar masses of all products x 100
atomic number Z
the number of protons in the NUCLEUS of an atom
atomic orbital
a region around the nucleus of an atom that can hold up to 2 electrons with opposite spins. a region around the nucleus where there is a high probability of finding an electron
average bond enthalpy
the average enthalpy change that takes place when breaking by homiletic fission 1 mol of a given type of bond in the molecules of a GASEOUS species
avogadro constant
Na, 6.02 x 10^23 mol-1, the number of atoms PER MOLE of carbon 12
avogadro’s hypothesis
equal volumes of gases at the same temperature and pressure contain the same number of molecules
base
a compound that neutralises an acid to form a salt
binary compound
a compound containing 2 elements only
bond angle
the angle between two bonds at an atom
bonded pair
a pair of electrons shared between 2 atoms to make a covalent bond
carbocation
an ion that contains a positively charged carbon atom
catalyst
a substance that increases the rate of a chemical reaction without being used up undergoing permanent change in the process. It provides an alternative route for the reaction with lower activation energy
cation
a positively charged ion with fewer electrons than protons
chain reaction
a reaction in which the propagation steps release new radicals that continue the reaction
cis-trans isomerism
a special type of E/Z isomerism in which there is a non-hydrogen groups and a hydrogen group around each carbon on the C-C double bond, the cis has H on each carbon on the same side whilst trans has hydrogen atoms on each carbon on different sides
closed system
a system isolated from its surroundings so the pressure, temperature and concentrations of the reactants and products are unaffected by outside influences
collision theory
two reacting particles must collide for a reaction to occur and be in the correct orientation and have sufficient energy to overcome the activation energy of the reaction
coordinate/dative covalent bond
a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only
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. they have been donated from the outer shells to a shared pool of electrons
desorption
release of an adsorbed substance from a surface, usually from a catalyst
dipole
a separation in electrical charge so that one atom of a POLAR covalent bond, or one end of a polar molecule has a partial positive charge d+ and the other a partial negative charge d-
dipole-dipole force
an ATTRACTIVE force between the permanent dipoles in NEIGHBOURING polar molecules
displacement reaction
a reaction in which a more reactive element displaces a a less reactive element from an aqueous solution of its ions
displayed formula
a formula that shows the relative positioning of all the atoms in a molecule and th bonds between them
disproportionation
when the same element is both reduced and oxidised simultaneously in the same redox reaction
dynamic equilibrium
the equilibrium that exists in a closed system where the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations don’t change
E/Z isomerism
a type of STERIOISOMERISM in which different groups attached to each carbon atom of a C-C double bond may be arranged differently in space because of the restricted rotation of the C-C double bond
electron config
a shorthand method of showing how electrons occupy sub-shells in an atom
electronegativity
a measure of the attraction of a BONDED atom for the pair of electrons in a covalent bond
electrophile
an atom or group of atoms that is attracted to an electron-rich centre where it accepts a pair of electrons
electrophilic addition
an addition reaction in which the first step is attack by an electrophile on a region of high electron density
elimination reaction
the removal of a molecule from a saturated molecule to make an unsaturated molecule
empirical formula
a formula that shows the simplest whole number ration of atoms of each element present in a compound
end point
the point in a titration where the indicator changes colour, indicating when the reaction is just complete
endothermic reaction
a reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings
enthalpy
the heat content stored in a chemical system
enthalpy change
difference in enthalpy between reactants and products in a reaction
system in a chemical reaction
the atoms, ion so or molecules making up the chemicals: reactants and products
surroundings in a chemical reaction
apparatus, the lab and everything that isn’t the chemical system
universe
everything including the system and surroundings
enthalpy cycle
a diagram showing alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess’ law
enthalpy profile diagram
a diagram for the reaction which compares the enthalpy of the reactants with the enthalpy of the products
equilibrium constant
a measure of the position of equilibrium- the magnitude of the Kc indicates whether there are more reactants or more products in an equilibrium system
exothermic reaction
a reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants resulting in heat loss to the surroundings
fingerprint region
An area of an IR spectrum below 1500cm-1 that gives a characteristic pattern for different compounds
first IE
the energy required to remove 1 e- from each atom in 1 mol of gaseous atoms of an element to form 1 mol of 1+ ions
fractional distillation
the separation of COMPONENTS in a liquid mixture by their different boiling points into fractions with different compositions
fragment ions
ions formed from the breakdown of the molecular ion in a MS
fragmentation
the process in MS that causes a positive ion to split into smaller pieces, one of which is a positive fragment ion
functional group
the group of atoms responsible for the characteristic reactions of a compound
general formula
the simplest algebraic formula for a member of a homologous series
giant covalent lattice
a three dimensional structure of ATOMS bonded together by strong covalent bonds
giant ionic lattice
a three dimensional structure of OPPOSITELY charged ions bonded together by strong ionic bonds
giant metallic lattice
a three dimensional structure of positive ions and delocalised electrons bonded by strong metallic bonds
group
a vertical column in the periodic table. the elements have similar chemical properties and the atoms have the same number of outer shell electrons
Hess Law
If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route
Heterogeneous catalysis
a reaction in which the catalyst has a different physical state from the reactants; frequently reactants are gases whilst the catalyst is a solid
heterolytic fission
the breaking of a covalent bond with both the bonded electrons going to one atom, forming a cation and an anion
homogeneous catalysis
a reaction in which the catalyst and reactants are in the same physical state, which is most frequently the aqueous or gaseous state
homologous series
a series of organic compounds with similar chemical properties and the same functional group, with each successive member differing by CH2
homolytic fission
the breaking of a covalent bond, with one of the bonded electrons going to each atom, forming 2 radicals
hydrated
a crystalline compound containing water molecules
hydrocarbon
a compound containing carbon and hydrogen only
hydrogen bond
a strong dipole-dipole interaction between an electron deficient hydrogen attached to an electronegative atom of one molecule and a lone pair of electrons on the electronegative nitrogen, oxygen or fluorine of a neighbouring molecule
hydrolysis
a reaction where water or an aqueous solution of a hydroxide that causes the breaking of a bond in a molecule resulting being split into two products, the H and OH being incorporated into the products
induced d-d interaction
attractive forces between induced dipoles in different molecules aka london forces
initiation
the first stage in a radical reaction where a covalent bond is broken by homolytic fission of a covalent bonds to form radicals
intermediate
a species formed during a reaction that reacts further and is not present in the final products
intermolecular forces
an attractive force between dipoles of molecules.Can be London forces, permanent d-d interactions or hydrogen bonding.
ion
a positively charged atom or a covalently bonded group of atoms (a polyatomic ion), where the number of electrons is different from the number of protons
ionic bonding
the electrostatic attraction between positive and negative ions
isotope
atoms of the same element with different number of neutrons and different masses
le Chatelier’s principle
when a system in dynamic equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium by changing the position of equilibrium
limiting reagent
the reactant not in excess, which will be used up first and stop the reaction
london forces
attractive forces between induced dipoles in different molecules
lone pair
an outer shell pi of electrons that is not involved in chemical bonding
mass number A
the sum of the number of protons and neutrons in the nucleus aka nucleon number
metallic bonding
the electrostatic attraction between positive metal ions and delocalised electrons
concentration
the amount of solute, in moles, dissolved in 1dm3 of solution
molar gas volume
the volume per mole of gas molecules at a stated temperature and pressure
molar mass M
the mass per mole of a substance, units mol-1
mole
the amount of any substance containing as many elementary particles as there are carbon atoms in exactly 12g of the C-12 isotope
molecular formula
a formula that shows the number and type of atoms of each element present in a molecule
molecular ion
the positive ion formed in MS when a molecule loses an electron
molecule
the smallest part of a covalent compound that can exist whilst retaining its chemical identity, consisting of 2+ atoms covalently bonded together
monomer
a small molecule that combines with many other monomers to form a polymer
neutralisation
the reaction between an acid and a base to form a salt
nomenclature
a system of naming compounds for effective communication
non-polar
with no charge separation across a bond or in a molecule
nucleon number
the number of protons and neutrons in an atom
nucleophile
an atom or group of atoms that is attracted to an electron deficient carbon atom, where it donates a pair of electrons to form a new covalent bond
nucleophilic substitution
a reaction in which a nucleophile is attracted to an electron deficient carbon atom and replaces an atom or groups of atoms on it
oxidation
loss of electrons or increase in oxidation number
oxidation number
a measure of the number of electrons that an atom uses to bond with atoms of another element. Derived from a set of rules
oxidation state
the oxidation number
oxidising agent
a reagent that oxidises (takes away electrons from) another species
pi bond
a bond formed by the sideways overlap of two p orbitals containing two electrons with the electron density concentrated above and below the line joining the nuclei of the bonding atoms
partial dissociation
the splitting got some of a species in solution into aqueous ions
pauling electronegativity value
a value assigned as a measure of the relative attraction of a bonded atom for the pair of electrons in a covalent bond
percentage yield
the conversion of starting materials into a desired product is expressed by this
periodicity
a repeating trend in properties of the elements across each period of the periodic table
periods
a horizontal row of elements in the periodic table. elements show trend in properties across a period
permanent dipole
a small charge difference that does not change across a bond, with positive and negative partial charges on the bonded atoms, the result of the bonded atoms having different electronegativities
permanent dipole-dipole interactions
attractive forces between the permanent dipoles in different molecules
polar molecule
a molecule with an overall dipole having taken into account any dipoles across bonds and the shape of the molecule
polar covalent bond
a bond with a permanent dipole, having positive and negative partial charges on the bonded atoms
polyatomic ion
an ion containing more than one atom
polymer
a large molecule formed from many thousands of repeat units of smaller molecules known as monomers
position of equilibrium
the relative quantities of reactants and products, indicating the extent of a reversible reaction at equilibrium
primary alcohol
an alcohol in which the -OH group is attached to a carbon atom that is attached to two or three hydrogen atoms
principal quantum number n
a number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells or energy levels
propagation
the steps that continue a free radical reaction, in which a radical reacts with a reactant molecule to form a new molecule and another radical, causing a chain reaction
proton number
the number of protons in the nucleus of an atom
radical
a highly reactive species with an unpaired electron
rate of reaction
the change in concentration of a reactant or a product in a given time
reaction mechanism
the sequence of bond breaking and bond forming steps that shows the path taken by electrons during a reaction
redox reaction
a reaction involving reduction and oxidation, the gaining and loss of electrons
reducing agent
a reagent that reduces (adds electrons to) another species
reduction
gain of electrons or a decrease in oxidation number
reflux
the continual boiling and condensing of a reaction mixture back to the original container to ensure that the reaction takes place without the contents of the flask boiling dry
relative atomic mass Ar
the weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of C-12
relative formula mass
the weighted mean mass of the formula unit of a compound compared with 1/12 of the mass of an atom of C-12
relative isotopic mass
the mass of an isotope compared with 1/12 of the mass of an atom of C-12
relative molecular mass
the weighted mean mass of a molecule of a compound compared with 1/12 of the mass of an atom of C-12
reversible reaction
a reaction that takes place in both ‘forward’ and ‘reverse’ directions
sigma bond
a bond formed by the overlap of one orbital from each bonding atom, consisting of two electrons and with the electron density centred around aline directly between the nuclei of the two atoms
salt
the product of a reaction in which the H+ ions from theca are replaced by metal or ammonium ions
saturated
containing single bonds only
saturated hydrocarbon
a hydrocarbon with single bonds only
second IE
the energy required to remove one e- from each ion in one mole of gaseous 1+ ions of an element to form on mole of gaseous 2+ ions
secondary
on a carbon atom to which two carbon chains are attached
primary
on a carbon atom at the end of a chain
secondary alcohol
An alcohol in which the -OH group is attached to a carbon atom that is attached to two carbon chains and one hydrogen atom
shell (electron shell)
a group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level
shielding effect
the repulsion between electrons in different inner shells, reducing the net attractive force between the positive nucleus on the outer shell of electrons
simple molecular lattice
a three dimensional structure of molecules, bonded together by weak intermolecular forces
skeletal formula
a simplified organic formula, with H atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups
specific heat capacity
the energy required to raise the temperature of 1g of a substance by 1K
standard enthalpy change of combustion
the enthalpy change that takes place when one mole of a substance reacts completely with O under standard conditions, with all reactants and products in their standard states
standard enthalpy change of formation
the enthalpy change that takes places when one mole of a compound is formed from its elements under standard conditions, with all reactants and products in their standard states
standard enthalpy change of neutralisation
the enthalpy change that accompanies the reaction of an acid by a base to form one mole of H20 under standard conditions, with all reactants and products in their standard states
standard enthalpy change of reaction
the enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states
standard solution
a solution of known concentration
standard state
the physical state of a substance under standard conditions of 100kPa and a stated temperature (usually 298K)
stereoisomers
compounds with the same structural formula but with a different arrangement of the atoms in space
stichiometry
the ratio of the amount, in moles, of each substance in a chemical reaction
strong acid
an acid that dissociates completely in solution
structural formula
a formula showing the minimal detail for the arrangement of atoms is a molecule
structural isomers
compounds with the same molecular formula but different structural formulae
sub-shell
a group of orbitals of the same type within a shell
substitution reaction
a reaction in which one atom or group of atoms is replaced by another atom or group of atoms
termination
the step at the end of a radical substitution when two radicals combine to form a molecule
tertiary
on a carbon atom to which three carbon chains are attached
tertiary alcohol
an alcohol in which the -OH group is attached to a carbon atom that is attached to no hydrogen atoms
theoretical yield
the yield resulting from complete conversion of reactants into products
unsaturated
containing a multiple carbon to carbon bond
water of crystallisation
water molecules that are bonded into a crystalline structure of a compound
weak acid
an acid that dissociates only partially in solution
