A2 chem definitions Flashcards
Co-ordination number of six
6 dative covalent bonds bonded to central metal atom/ion
Electron affinity
E change when 1 e- is added to each atom in 1 mole of gaseous atoms
Lattice Energy
Enthalpy change when 1 mole of solid ionic compound is formed from its gaseous ions under standard conditions
Enthalpy change of solution
Energy change when 1 mole of solute is dissolved in an infinite amount of water to form a dilute solution
Enthalpy change of atomisation
Energy change when 1 mole of gaseous atoms are formed from its element in standard state
Enthalpy change of hydration
Energy change when 1 mole of gaseous ions is dissolved in an excess of water
Bond Energy
The energy change when 1 mole of covalent bonds is broken in gaseous state
Weak acid
An acid that is partially ionised
Amphoteric
Can react with an acid or base
Standard cell potential
Potential difference between 2 half cells under standard conditions of 1 atm, 298K, solutions being 1moldm^-3
Standard electrode potential
Potential difference when a half cell is connected to standard hydrogen electrode under standard conditions of 1 atm, 298K, solutions being 1moldm^-3
Rate of reaction
Change in amount of reactants per unit time
Half-life of a reaction
The time is taken for the amount of reactant to halve
Rate-determining step
Slowest step in the overall reaction
Heterogenous
Different states
Homogenous
Same States
Heterogenous catalyst
Catalyst and the reactants are in the same phase
Entropy
Measure of disorder of a system
△G
Gibbs Free Energy change
Order of reaction
The power to which the conc of a reactant is raised in the rate equation
Reversible reaction
Reaction that can go in either direction
Dynamic equilibrium
Rate of forward reaction = Rate of reverse reaction.
The concentration of all species remain unchanged
Partition coefficient, Kpc / Kpartition
Ratio of concentration of a solute in the two immiscible solvents at equilibrium
Transition element
Element that forms 1 or more stable ions with partially filled d-orbital
Ligand
Species that uses LP to form dative covalent bonds to a central metal atom or ion
Monodentate ligand
A species that donates a LP of e- to central metal atom or ion
Bidentate ligand
An ion/molecule that donates 2 LPs of e- to central metal atom/ion
Polydentate ligand
A species that donate more than 1 LPs of e- to central metal atom/ion
Bidentate
An ion/molecule that donates 2 LPs of e- to central metal atom/ion
Complex ion
An ion formed by a central metal atom/ion bonded to one or more ligands
Degenerate
Orbitals have the same E
Coordination number
The no. of dative covalent bonds formed by the central metal atom/ion
Stability constant
Equilibrium constant for the formation of a complex ion in a solution
Structural isomer
Same number and type of atoms but different structural formula
Chiral centre
A carbon atom that has 4 different atoms or groups attached it
Stereoisomerism
Compounds that have the same structural formula but different spacial arrangements
Buffer solution / Buffer
A solution that resists the change of pH when a small amount of acid or alkali is added to it
Electronegativity
The attraction by an atom of the e- in a bond
Homolytic fission
Breaking of a bond to form two radicals
Free radical
Species with an unpaired e-
Protein
A polymer of amino acids joined by peptide bonds
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Secondary structure
alpha-helix / beta-sheet
Tertiary structure
folding of chains / 3D shape
Polymerisation
Many monomers forming a polymer
Condensation polymer
A polymer formed by the elimination of a small molecule
Double helix
Two interlinked spirals
Nano-sized
Measured in nm, btw (10^-9 to 10^-6)
Nanosphere
Spheres with a diameter in the nanometre range
Retention time
Time take for a compound to travel through the column
Partition
Separation due to the different solubilities of the compounds in two phases
Adsorption
Separation due to the different attractions between the compounds and the stationary phase, relative to their solubility in the solvent
Rf value
Distance travelled by a compound from baseline over the distance travelled by the solvent front
Zwitterion
Species having positive and negative ionic charges but no overall charge
Hydrophobic
Cannot form bonds with water molecules
Density of a substance
Mass per unit volume
Transition metal complex
Ion or molecule formed by a central metal atom/ion and surrounded by 1 or more ligands
Electronegativity, and how it relates to the concept of bond polarity
Electronegativity is the attraction by an atom of the electrons in a bond.
Bond polarity is the difference in electronegativities at each end of the bond.
