chemistry definitions Flashcards
define nucleophile
an e- pair donor
define electrophile
an e- pair acceptor
define free radicals
species with an unpaired e-
define homologous series
family of similar compounds with the same functional grp and similar chemical properties, with successive members differing by the addition of a CH2 grp
define functional grp
part of the compound that determines its chemical characteristics
define orbital
region around the nucleus that can hold up to 2 e-s with opposite spins
define enthalpy change of combustion
enthalpy change when 1 mol of substance combusts completely with O2
define enthalpy change of formation
enthalpy change when 1 mol of compound formed form its elements
define enthalpy change of neutralisation
enthalpy change when 1 mol of water formed from reaction between acid and base
define enthalpy change of reaction
overall energy taken in/given to surroundings when reactants react together
define structural isomer
same molecular formula, diff. structural formula
define aromatic compound
compounds containing benzene ring
define alicyclic compound
aliphatic compound arranged in non-aromatic rings (cyclic structure without benzene ring)
define aliphatic compound
compound containing C and H atoms joined in straight or branched chains / in non-aromatic rings
define heterlotytic fission
when covalent bond breaks unevenly (1 atom takes both of the shared e-s), forming +tive and -tive ions
define hommolytic fission
when covalent bond breaks evenly, each atom takes 1 e- from the shared pair, forming 2 free radicals
define curly arrows
shows the movement of an e- pair
define homogeneous catalyst
catalyst in the same physical state (phase) as reactants, finds alternative reaction pathway with lower activation energy
define heterogeneous catalyst
catalyst in the diff. physical state (phase) as reactants, finds alternative reaction pathway with lower activation energy
define polymerisation
monomers joined together to long repeating units (polymer)
define electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond towards itself
define le chatielier’s principle
The position of the equilibrium of a system changes to minimise the effect of any imposed change in conditions
define precipitate
a solid formed by a change in a solution that decreases solubility of a solid
define disproportionation
a reaction in which the same element is both oxidised and reduced
define dynamic equilibrium
forward reaction happening at same rate as backwards reaction, concs of both reactants + products remain constant
define an arene
an aromatic compound (contains a benzene ring)
define a carbocation
positively charged carbon atoms with only three covalent bonds instead of four
define stoichiometry
the relative quantities of substances in a reaction.
define markownicoff’s law
When a hydrogen halide reacts with an unsymmetrical alkene the hydrogen of the hydrogen halide bonds to the C atom with the most H atoms already bonded
define hess’ law
the enthalpy changeof a reaction is independentof the routetaken
define primary alcohol
the carbon atom bonded to the -OH group is attached to ONE other carbon atom (or alkyl group)
define secondary alcohol
The carbon atom the -OH group is bonded to is bonded to TWO alkyl groups
define tertiary alcohol
The carbon atom the -OH group is bonded to is bonded to three alkyl groups.
define average bond enthalpy
the average amount of energy needed to break a specific type of bond
what are the standard conditions?
1 atm (100KPa)
25 degrees celcius/298 K
define fragmentation
a type of chemical dissociation, in which the removal of the electron from the molecule results in ionization
