A level Definitions Flashcards
Relative Isotopic Mass
The mass of an atom of an isotope compared with 1/12th mass of carbon-12
Relative Atomic Mass (Ar)
The weighted mean mass of an atom of an element compared with 1/12th mass of carbon-12
Isotopes
Atoms of an element with the same number of protons but different number of neutrons.
Molar Mass
Mass per mole units g mol^-1
Mole
The amount of substance 1 mole is 6.02 x 10^23 particles
Acid
Releases H+ ion aqueous solution
Alkali
A soluble base that releases OH- ions in an aqueous solution.
Strong Acid
Fully dissociates in solution
Weak Acid
Partially dissociates in solution
Orbital
A region around the nucleus that can hold up to two electrons, with opposite spins
Disproportionation
Oxidation and reduction of the same element
First Ionisation Energy
The energy needed to remove 1 mole of electrons from 1 mole gaseous of atoms to form one mole of gaseous 1+ ions.
Ionic bonding
The electrostatic attraction between oppositely charged ions. (usually between a metal and non-metal)
Covalent Bonding
Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms ( 2 non-metals)
Polar molecule
Compound has polar bonds with dipoles that do not cancel due to their direction
Metallic bonding
The electrostatic attraction between positively charged metal ions and the sea of delocalised electrons.
Electronegativity
the ability of an atom to attract the bonding electrons in a covalent bond
Standard states
physical states under standard conditions
Standard conditions
Temperature: 298 kelvin Pressure: 100 KPa
Enthalpy change of formation
The enthalpy change when one mole of a compound is formed from its elements in their standard states
Enthalpy change of combustion
The enthalpy change for the complete combustion of one mole of a substance
Enthalpy change of neutralisation
The enthalpy change for the formation of 1 mol of water from a neutralisation reaction
Activation energy
the minimum energy required for a reaction to take place
Homologous Series
(a series of organic compounds having) the same functional group but with each successive member differing by CH2
Structural isomers
Compounds with the same molecular formula but different structural formula
Homolytic fission
Breaking a covalent bond to form two radicals
Heterolytic fission
Breaking a covalent bond to form two oppositely charged ions
E/Z isomerism
an example of stereoisomerism, due to restricted rotation about a double bond and two different groups attached to each carbon atom of the C=C group
Cis-trans isomerism
A special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same
Electrophile
An electron pair acceptor
Nucleophile
An electron pair donor
Homogeneous catalyst
A catalyst in the same state as the reactants (usually in solutions)
Heterogeneous catalyst
- A catalyst in a different state to the reactants (usually a solid catalyst with reactants in solution or gas)
Dynamic equilibrium
When the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of reactants and products do not change in a closed system
Catalyst
Chemical that increases the rate of both forward and reverse reactions in an equilibrium by the same amount resulting in an unchanged position of equilibrium
σ-bond
Overlap of orbitals directly between the bonding atoms
π-bond
Sideways overlap of adjacent p-orbitals above and below the bonding C atoms
Stereoisomerism
Compounds with the same structural formula but a different arrangement of atoms in space
Curly arrow
Shows the movement of an electron pair during a reaction
Rate of reaction
the rate at which the concentration of a reactant or product is formed/used
Half-life
The time taken for the concentration of a reactant to half
Rate-determining step
the slowest step in a multistep reaction
Brønsted-Lowry acid
a species that donates a proton (H+)
Brønsted-Lowry base
a species that accepts a proton (H+)
Buffer solution
a system that minimises pH changes on addition of small amounts of an acid or a base
Lattice Enthalpy
enthalpy change for the formation of 1 mole of ionic lattice from gaseous ions, ΔLEH
Enthalpy change of solution
enthalpy change for dissolving of 1 mol of solute, ΔsolH
Enthalpy change of hydration
enthalpy change for dissolving of 1 mol of gaseous ions in water, ΔhydH
Oxidising agent
the chemical that is reduced and oxidises another species
Reducing agent
the chemical that is oxidised and reduces another species
Standard electrode (redox) potential, Eo
the voltage produced when a half cell is connected to a standard hydrogen half-cell, measured at 298K with solution concentrations of 1 mol dm^-3 and a gas pressure of 100KPa.
Ligand
species that donates a pair of electrons forming a coordinate/dative covalent bond to a metal ion
Optical isomer
non-superimposable mirror images about a chiral centre
