definitions Flashcards
The d-block transition metals
metals with an incomplete d subshell in at least one of their ions.
ligands
Ligands may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds.
coordination number
The total number of bonds from the ligands to the central transition metal is known as the coordination number.
The equilibrium constant ( K )
characterises the equilibrium composition of the reaction mixture.
ionic product
The dissociation constant for the ionisation of water
buffer
A buffer solution is one in which the pH remains approximately constant when small amounts of acid, base or water are added.
The standard enthalpy of formation, ∆H °f
the enthalpy change when one mole of a substance is formed from its elements in their standard states.
standard state
The standard state of a substance is its most stable state at a pressure of 1 atmosphere and at a specified temperature, usually taken as 298 K.
entropy
The entropy (S) of a system is a measure of the degree of disorder of
the system.
The second law of thermodynamics
The second law of thermodynamics states that the total entropy of a reaction system and its surroundings always increases for a spontaneous process.
The third law of thermodynamics
The third law of thermodynamics states that the entropy of a perfect crystal at 0 K is zero.
The standard entropy of a substance
The standard entropy of a substance is the entropy value for the substance in its standard state.
a feasible reaction
A feasible reaction is one that tends towards the products rather than the reactants
The order of a reaction with respect to any one reactant
The order of a reaction with respect to any one reactant is the power to which the concentration of that reactant is raised in the rate equation.
The overall order of a reaction
The overall order of a reaction is the sum of the powers to which the concentrations of the reactants are raised in the rate equation.
hybridisation
Hybridisation is the process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals. These hybrid orbitals are degenerate.
chromophore
A chromophore is a group of atoms within a molecule that is responsible for absorption of light in the visible region of the spectrum.
a conjugated system
a system of adjacent unhybridised p orbitals that overlap side-on to form a molecular orbital across a number of carbon atoms.
nucleophiles
negatively charged ions or neutral molecules that are electron rich
electrophiles
positively charged ions or neutral molecules that are electron deficient
SN1
SN1 is a nucleophilic substitution reaction with one species in the rate determining step and occurs in a minimum of two steps via a trigonal planar carbocation intermediate.
SN2
SN2 is a nucleophilic substitution reaction with two species in the rate determining step and occurs in a single step via a single five-centred, trigonal bipyramidal transition state.
DRUGS
Drugs are substances that alter the biochemical processes in the body.
agonist
An agonist mimics the natural compound and binds to the receptor molecules to produce a response similar to the natural active compound.
