Definitions Flashcards
Enthalpy change of reaction
The energy change associated with a given reaction
Enthalpy change of formation
The energy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard conditions
Exotherminc process
Enthalpy change of combustion
The energy change that takes place when one mole of a substance is completely combusted
Enthalpy change of neutralisation
The energy change that takes is associated with the formation of 1 mole of water from a neutralisation reaction
Standard enthalpy change of atomisation
The energy change that takes place when one mole of gaseous atoms is formed from its element in its standard state
Endothermic process
First ionisation energy
The energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions
Endothermic process
First electron affinity
The energy required to add electrons to atoms to form one mole of gaseous 1- ions from gaseous atoms
Exothermic process because electron is attracted into the outer shell of an atom by the nucleus
Second electron affinity
The energy required to add electrons to form one mole of gaseous 2- ions from gaseous 1- ions
Endothermic process because the electron is repelled by the 1- ion and this repulsion has to be overcome
Relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon 12
Relative atomic mass
The weighted mean mass of an atom of an element compared with one twelfth the mass of an atom of carbon 12
A mole
The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon 12 isotope
Activation energy
The minimum energy required to start a reaction by breaking bonds in the reactants
Amphoteric substances
substances that can react as both acids and bases e.g amino acids
Atomic orbital
A region of space where it is likely you will find electrons. Each orbital can hold up to 2 electrons with opposite spins.
Average bond enthalpy
The mean energy needed for 1 mole of a given type of gaseous bonds to undergo homolytic fission.
cis-trans isomerism
a type of E/Z isomerism where two substituent groups attached to each carbon atom of the C=C is the same
Covalent bond
A bond formed by a shared pair of electrons between nuclei
Dative covalent bond
A bond formed by a shared pair of electrons that has been provided by one of the bonding atoms only.
Displayed formula
A formula which shows the relative positioning of atoms and the bonds between them.