Glossary deck Flashcards
All terms
activated complex
a stage reached in a reaction where an intermediate product is formed
activation energy
the minimum amount of kinetic energy needed by reactants before the reaction can occur
aldehydes
flavour molecules with the carbonyl functional group on the end of carbon
amino acids
molecules with an amino group and carboxyl group
antioxidants
reduce the oxidation of chemicals in foods
atom economy
compares the proportion of reactant atoms that end up in a useful product to the number that ended up as waste
Bond enthalpy
the energy required to break one mole of bonds between the atoms in a mole of gaseous diatomic molecules, at standard temp 25 and pressure 1 atmosphere
Bonding continuum
a scale that has ionic bonding at one end and pure covalent at the other, with polar covalent in between
chromatography
a technique which can be used to separate, identify and in some instances obtains individual substances from comlex mixtures
collision geometry
the angle at which molecules collide
collision theory
simple collision theory states that for reactants to form products they must first come in contact with each other (collide)
concordant titres
reaings which are within 0.2cm³ of each other
covalent network
a giant 3D structure in which all of the atoms are covalently bonded to each other
covalent radius
half the distance between the nuclei of two atoms joined by a single covalent bond
delocalised electrons
outer electrons which can move easily from one atom to another
denature
breaking of hydrogen bonds in protein resulting in loss of shape of molecules
diols
alcohols with 2 hydroxyl groups
dynamic equilibrium
the point where, in a reversible reaction, the rate of the forward reaction equals the rate of the reverse reaction
electronegativity
the attraction an atom involved in a bond has for the electrons of the bond
emulsifier
substance which enables normally immiscible liquids to mix
emulsion
a mixture of two or more liquids which are normally immiscible
energy distribution diagram
a graph of the no. of molecules against kinetic energy, which shows how the energy of the reactants varies at a particular temperature
enthalpy change
change in energy which accompanies a chemical reactin
enzyme
biological catalyst; most enzymes are proteins
essential amino acids
amino acids needed by the body but which the body cannot make so gets from food
essential oils
the concentrated extracts of the volatile non-water soluble aroma compounds found in plants
ester link
bond formed between a carboxylic acid molecule and alcohol molecule when they react to form an ester
fats and oils
naturally occuring esters found in animals and plants
fatty acids
long-chain carboxylic acids found in fats and oils
first ionisation energy
the energy required to remove one mole of electrons from one mole of atoms in the gaseous state.
fragrances
pleasant, sweet-smelling smells, caused by essential oils in plants
free radicals
reactive particles which have unpaired electrons
free radical chain reaction:
(1) initiation
(2) propagation
(3) termination
reaction in which free radicals react in three distinct phases:
(1) the first step where free radicals are formed when a molecule absorbs radiation
(2) steps where free radicals react to form further free radicals that can themselves react
(3) step n which free radicals combine, slowing the rate and stopping the reaction
free radical scavenegers
substances that remove free radicals and stop chain reactions
fullerene
a molecular form of carbon (C₆₀)
glycerol
propane-1,2,3-triol, an alcohol with three hydroxyl groups, found in fats and oils
green chemistry
the design of a chemical products and processes that reduce or eliminate the use and production of hazardous substances
hydrogen bond
when hydrogen is bonded to oxyge, nitrogen or fluorine it results in a very strong permanent dipole - permanent dipole attration between molecules are called a hydrogen bond
hydrolysis
the breaking down a compund which involves the addition of the elements in water
hydrophilic
water loving
hydrophobic
water hating
intermolecular forces
attractions between molecules
ketones
flavour molecules where the carbonyl qroup is not on the end carbon
london dispersion forces
forces of attraction caused by temporary dipoles in neighbouring atoms or molecules
mean bond enthalpy
the average bond energy, takign into account the environment of the atoms forming the bond
miscibility
the ability of liquids to mix in all proportions, forming a solution
molar volume
the volume occupied by one mole of a gas when measured ata given temp and pressure
monatomic
a substance that exists as individual non-bonded atoms (noble gases)
oxidising agent
accepts electrons from a reactant and so oxidises it
peptide link
bond formed between 2 amino acids when they react - also known as the amide link
percentage yield
compares the expected product quantity with the actual amount produced
periodicity
repeating patterns in the periodic table
permanent dipole - permanent dipole
forces of attraction occuring between molecules with permanent dipoles
polar covalent
the bond formed when two atoms share electrons unequally resulting in permanent dipoles
primary alcohols
the carbon atom woth the hydroxyl group is attached to one other carbon atom
proteins
natural condensation polymers made up of amino acids
pure covalent
the bond formed when 2 atoms share bonding electrons equally
reducing agent
supplies electrons to a reactant in order to reduce it
reversible reaction
a reaction which can take place in both directions i.e. the products can re-form reactants
secondary alcohols
the carbon atom with the hydroxyl group is attached to two other carbon atoms
soap
salt of long chain fatty acids made from fats and oils
solvent front
the distance travelled by the solvent in chromatography
standard enthalpy of cimbustion
the enthalpy change when one mole of a substance burns completely, measured at standard temp and pressure all substances being in their standard states
standard solution
a solution of accuarately known concentration
sun block
mixtures containing compounds which reflect UV light and stop it reaching the skin
terpenes
molecules that can be viewed as being based on isoprene (2-methylbuta-1,3-diene) units joined together
tertiary alcohols
the carbon with the hydroxyl group is attached to 3 other carbon atom s
triols
alcohols with three hydroxyl groups
ultraviolet (UV) light
high energy radiation which causes many chemical reactions in our skin
van der waals forces
intermolecular forces of attraction
london dispersion forces, permanent dipole - permanent dipole interactions including hydrogen bonding
