Definitions Flashcards
The enthalpy of formation
The standard enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions, and all reactants and products in their standard states.
The enthalpy of combustion
The standard enthalpy change when one mole of a substance is burned completely in oxygen.
The enthalpy of atomization
The standard enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state.
The first ionisation energy
The enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge
The second ionisation energy
The enthalpy change when one mole of positively charged gaseous ions loses a mole of electrons.
The first electron affinity
The enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions, each with a negative charge.
The second affinity
The enthalpy change when a mole of electrons is added to a mole of gaseous ions each with a single negative charge to form ions each with two negative charges.
Lattice enthalpy of formation
The standard enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions.
Lattice enthalpy of dissociation
The standard enthalpy change when one mole of solid ionic compound dissociated into its gaseous ions.
Enthalpy of hydration
The standard enthalpy change when water molecules surround one mole of gaseous ions
Enthalpy of solution
The standard enthalpy change when one mole of solute dissolves completely in solution in sufficient solvent to form a solution in which molecules or ions are far enough apart to not interact with each other.
Mean bond enthalpy
The enthalpy change when one mole of gaseous molecules each breaks a covalent bond to form two free radicals averaged over a range of compounds.
Define Brønsted-Lowry acid
Proton Donor
Define Lewis acid
Electron pair acceptor
Define Acid derivative
Organic compound related to a carboxylic acid with the formula RCOZ where RCO represents an acyl group and Z = Cl, NHR, OR, or OCOR.
Define activation energy
The minimum energy that a particle needs in order to react; the energy difference between the reactants and the transition state.
Define aldehyde
An organic compound containing the general formula
RCHO
What are the alkaline earth metals
The metals in Group 2 of the periodic table
Define alkane
A hydrocarbon with C-C and C-H single bonds only with the general formula CnH2n+2
Define allotropes
Pure elements which can exist in different physical forms in which their atoms are arranged differently. for example, diamond, graphite, and buckminsterfullerene are allotropes of carbon.
Define anaerobic respiration
The process by which energy is released and new compounds are formed within living organisms in the absence of oxygen.
Define Atom Economy
Describes the efficiency of the reaction by comparing the total number of atoms in the product with the total number in starting materials.
Define Atomic orbital
A region of space around an atomic nucleus where there is a high probability of finding an electron.
Define Avogadro constant
Number of particles in a mole
6.022x1023
Define Brønsted-Lowry base
Proton acceptor
Define Lewis Base
Electron pair donor
Define Base peak
The ion with the greatest abundance (tallest peak) in a mass spectrum
Define Bond dissociation enthalpy
The enthalpy change to break a covalent bond in all the species in the gaseous state
Define Buffer
A solution which resists changes to the pH when small amounts of acid/base are added to it.
In the image, only solution B is the buffer.
Define Calorimeter
An instrument for measuring the heat changes that accompany chemical reactions
Define Carbocation
An organic ion in which one of the carbon atoms has a positive charge.
Define Carbon-neutral
A process, or series of processes, in which as much carbon dioxide is absorbed from the air as is given out.
Define Catalyst
A substance that alters the rate of a chemical reaction but is not used up in the reaction.
Define Catalytic Cracking
The breaking, with the aid of a catalyst normally a zeolite of long-chain alkane molecules (obtained from crude oil) into shorter hydrocarbons. The reaction forms an ionic indeterminate. It also may produce some alkenes.
Define Chelation
The process by which a multidentate ligand replaces a monodentate ligand in forming co-ordinate (dative) bonds to a transition metal ion.
Define Chemical feedstock
The starting materials in an industrial chemical process.
Define Chiral
This means ‘handed’. A chiral molecule exists in two mirror-image forms that are not superimposable.
Define Chiral Centre
An atom to which 4 different atoms or groups are bonded.
Define Co-ordinate bond
A covalent bond in which both electrons in the bond come from one of the atoms. (Also known as a dative bond)
Define Co-ordination number
The number of ligand molecules bonded to a metal ion.
Define Covalent bonding
A chemical bond where two atoms share a pair of electrons between them.
Define Delocalisation
The process by which electrons are spread over several atoms and help bond them.
Define Dipole-dipole forces
An intermolecular force that results from the attraction between molecules with permanent dipoles.
Define displacement reactions
A chemical reaction in which one atom replaces another atom in a compound.
Define displayed formula
The formula of a compound drawn out so that each atom and each bond is shown
Define Disproportionation
Redox Reaction in which the oxidation number of an element both increases and decreases.
Define Dynamic Equilibrium
Constant concentration as forward reaction rate = bascward reaction rate.
