All IEB Definitions for Chemistry Flashcards
Molar mass
the mass in grams of one mole of that substance.
Solution
a homogenous mixture of solute and solvent.
Solute
the substance that dissolved in the solution.
Solvent
the substance in which another substance is dissolved, forming a solution.
Concentration
the amount of solute per unit volume of solution.
Yield
a measure of the extent of a reaction, generally measured by comparing the amount of product against the amount of product that is possible.
Intramolecular bond
a bond which occurs between atoms within molecules.
Intermolecular force
a force of attraction between molecules, ions, or atoms of noble gases.
Covalent bond
a sharing of at least one pair of electrons by two non-metal atoms.
Non-polar covalent (pure covalent)
an equal sharing of electrons.
Polar covalent
an unequal sharing of electrons leading to a dipole forming.
Ionic bond
a transfer of electrons and subsequent electrostatic attraction.
Metallic bonding
bonding between a positive kernel and a sea of delocalised electrons.
Electronegativity
a measure of the tendency of an atom to attract a bonding pair of electrons.
Organic molecules
molecules containing carbon atoms.
Hydrocarbon
a compound containing only carbon and hydrogen atoms.
Homologous series
a series of similar compounds which have the same functional group and have the same general formula, in which each member differs from the previous one by a single CH2 unit.
Saturated compound
a compound in which all of the bonds between carbon atoms are single bonds.
Unsaturated compound
a compound in which there is at least one double and/or triple bond between carbon atoms.
Functional group
an atom or a group of atoms that form the centre of chemical activity in the molecule.
Structural isomers
compounds having the same molecular formula but different structural formulae.
Heat of reaction (ΔH)
the net change of chemical potential energy of the system.
Exothermic reactions
reactions which transform chemical potential energy into thermal energy.
Endothermic reactions
reactions which transform thermal energy into chemical potential energy.
Activation energy
the minimum energy required to start a chemical reaction or the energy required to form the activated complex.
Activated complex
a high energy, unstable, temporary transition state between the reactants and the products.
Reaction rate
the change in concentration per unit time of either a reactant or product.
Catalyst
a substance that increases the rate of the reaction but remains unchanged at the end of the reaction.
Closed system (in chemistry)
a system in which mass is conserved inside the system but energy can enter or leave the system freely.
Open system (in chemistry)
a system in which both energy and matter can be exchanged between the system and its surroundings.
Le Châtelier’s principle
when an external stress (change in pressure, temperature or concentration) is applied to a system in dynamic chemical equilibrium, the equilibrium point will change in such a way as to counteract the stress.
Lowry-Brønsted theory
an acid is defined as a proton donor. A base is defined as a proton acceptor.
Ionisation
the reaction of a molecular substance with water to produce ions.
Strong acid
an acid that ionises completely in an aqueous solution.
Weak acid
an acid that only ionises partially in an aqueous solution.
Dissociation
the splitting of an ionic compound into its ions.
Strong base
a base that dissociates completely in an aqueous solution.
Weak base
a base that only dissociates/ionises partially in an aqueous solution.
Amphoteric (amphiprotic) substance
a substance that can act as either an acid or a base.
Neutralisation (equivalence point)
the point where an acid and base have reacted so neither is in excess.
Salt
a substance in which the hydrogen of an acid has been replaced by cation.
Hydrolysis of a salt
a reaction of an ion (from a salt) with water.
Standard solution
a solution of known concentration.
Redox reaction
a reaction involving the transfer of electrons.
Oxidation
the loss of electrons.
Reduction
the gain of electrons.
Oxidising agent
a substance that accepts electrons.
Reducing agent
a substance that donates electrons.
Anode
the electrode where oxidation takes place.
Cathode
the electrode where reduction takes place.
Electrolyte
a substance that can conduct electricity by forming free ions when molten or dissolved in solution.
