Definitions Flashcards
Isotopes
Atoms of the same element that have a different number of neutrons
Relative isotopic mass
Mass of an atom of an isotope compared to 1/12 the mass of an atom of carbon-12
Relative atomic mass
Weighted mean mass of an atom compared to 1/12 the mass of an atom of carbon-12
Mole
Amount of any substance that has the same number of particles as exactly 12g of carbon-12
Molar mass
Mass of 1 mol of substance
Salt
Chemical compound formed when the H ion of an acid is replaced with a metal or ammonium ion
Hydrated
Contains waters of crystallisation
Water of crystallisation
Water molecules in an ionic lattice
Acid
Proton donor
Base
Proton acceptor
Alkali
Soluable base
Disproportionation
A reaction where the same element both oxidises and reduces
1st Ionisation energy
Energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of +1 gaseous ions
Orbital
A region of space which can take a max of 2 electrons with paired opposing spins
Isoelectric
Same electron arrangement but different elements
Covalent bonding
The electrostatic attract between the positive nuclei of one atom and a pair of shared electrons
Dative covalent bond
When one atom supplies both electrons for the bond
Ionic bonding
The electrostatic attraction between oppositely charged ions
Electronegativity
The ability of an element to attract a pair of electrons from a bond
Periodicity
A property that has a pattern across a period that is repeated across successive periods
Giant structure
Has no fixed size so can continuously add atoms to the same structure
Average bond enthalpy
Energy required to break one mole of bonds in a gaseous molecule
Standard enthalpy change of formation
The enthalpy change when one mole of a compound is made from its elements in their standard state under standard conditions (1 atm and 25 degrees)
Standard enthalpy change of combustions
Enthalpy change when one mole of substance undergoes complete combustion under standard conditions
Standard enthalpy change for neutralisation
Enthalpy change on the formation of one mole of water from the neutralisation of acid with an alkali under standard conditions
Hesse’s law
States that an enthalpy change for a reaction is independant of the route taken (providing the initial and final condition are the same)
Heterogenous catalyst
A catalyst that is in a different phase (physical state) to the reactants
Homogenous catalyst
Same phase as reactants
Dynamic equilibrium
A reversible reaction where the rate of the forward reaction is equal to the rate of the backward reaction
Structural isomers
Same molecular formule but different structural formula
Aliphatic
Straight chains only
Homologous series
Compounds with the same functional group and general formula but successive members differ by CH2
Functional group
An atom or group of atoms in a compound that determine the characteristic reactions of the molece
Radical
An atom of group of atoms with an unpaired electron
Homolytic fission
Each bonding atom receives one electron from the bonding pair forming two radicals
Isomer
Compounds with the same molecular formula but different chemical structures
Stereoisomers
Same structural formula but a different arrangement in space
Electrophile
An electron pair acceptor
Makownikoff’s rule
The carbocation with the most alkyl groups on the C with the + sign will form as it will be the most stable
Nucleophile:
An electron pair donor
Volatility
Indicates how easily a liquid will change into a gas
Le Chatelier’s principle
The position of equilibrium will shift so as to minimise the effect of any change in condition
