Exam Definitions Flashcards
Boiling point
The temperature of a liquid at which its vapour pressure equals the external atmospheric pressure
Temperature
The average kinetic energy of particles
Ionisation energy
The energy required per mole to remove an electron from an atom in the gaseous phase
Electron affinity
The amount of energy released when a neutral atom accepts an additional electron to form an anion
Electronegativity
A measure of the tendency of an atom in a molecule to attract a bonding pair of electrons
Mole
The amount of substance having the same number of particles as there are atoms in 12g of carbon-12
Molar mass
The mass in grams of one mole of that substance
Solution
Homogenous mixture of solvent and solute
Solute
The substance that is dissolved in the solution
Solvent
The substance in which another substance is dissolved, forming a solution
Molar concentration
The amount of solute per unit volume of solution
Intramolecular bond
Bond between atoms within molecules
Covalent bond
Involves the sharing of at least one pair of electrons by 2 atoms
Ionic bond
Involves the transfer of electrons to form cations and anions which are electrostatically attracted in an ionic crystal latice
Metallic bonding
The attraction between positive kernels and a delocalised sea of electrons
Intermolecular force
The force of attraction between molecules or between atoms of a noble gas
Polar Molecule/Dipole
Molecule in which the electrons are unevenly distributed resulting in a δ- and δ+ end
Heat of reaction
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
Activated complex
A high energy, unstable transition state between the reactants and the products
Reaction rate
The change in the amount of concentration per unit time of either reactant or product
Catalyst
A substance that increases the rate of the reaction but remains unchanged at the end of the reaction
Collision Theory
A model that explains that a reaction will only proceed when reactant particles collide effectively
Limiting reagent
The substance that is totally consumed or consumed first during a chemical reaction
Closed system
A system in which mass is conserved inside the system but energy can enter or leave the system freely
Open system
A system in which both energy and matter can be exchanged between the system and its surroundings
Reversible reaction
A reaction in which products can be converted back into reactants.
Dynamic equilibrium
A reversible reaction in which the forward and the reverse reactions are occurring simultaneously at the same rate
Le Châtelier’s Principle
When an external stress is applied to a system in dynamic chemical equilibrium, the equilibrium point will change in such a way as to counteract the stress
