Chemistry Definitions - Grade 11 and 12
Grade 11
Intramolecular force - the bond found between the atoms in a molecule (covalent/ionic/metallic)
Covalent bond - the sharing of at least 1 pair of electrons by two non-metal atoms
Ionic bond - the transfer of electrons and subsequent electrostatic attraction
Metallic bond - an electrostatic force of attraction between a positive kernel and a sea of
delocalised electrons
Intermolecular force - the weak forces of attraction that exist between molecules (van der Waal)
London’s forces - found between all molecules due to a temporary shift in the electron cloud
causing a temporary dipole
Dipole-dipole - found between polar molecules due to a difference in electronegativity
Hydrogen bonding - where H is bonded to small, high electronegative atoms which contain at
least 1 lone pair (H -> N, O, F)
Electronegativity - a measure of the tendency of an atom to attract a bonding pair of electrons
Bond energy - the energy required to break a bond between 2 atoms
Polar covalent - a bond formed where there is an unequal sharing of electrons
(different electronegativities)
Exothermic reaction - transforms chemical potential energy into thermal energy (energy release)
Endothermic reaction - transforms thermal energy into chemical potential energy (absorb energy)
Activated complex - a temporary high energy, unstable transition state between the reactants and
the products
Neutralisation - occurs at the point where the acid and base have reacted so that neither is in
excess
Lowrey-bronsted - acid donates a H+ base accepts a H+
Grade 12
Reversible reaction - a reaction where the products can be converted back to reactants
Open system - a system in which matter and energy can be exchanged between the system and
its surroundings
Closed system - a system in which mass is converted inside the system, but energy can enter or
leave the system freely
Reaction rate - the change in concentration per unit time of either a product or a reactant
Le Chatelier's Principle - when an external stress is applied to a system in dynamic equilibrium,
the equilibrium point will change in such a way as to counteract the stress
Equilibrium constant = [products]/[reactants] aA + bB -> cC + dD ( [C]c + [D]d )/( [A]a + [B]b)
Use RICE table for calculations (Ratio, initial, change, end moles)
Oxidation - the loss of electrons (reducing agent) (occurs at the anode)
Reduction - the gain of electrons (oxidising agent) (occurs at the cathode)
Galvanic cells - an electrochemical cell that converts chemical energy to electrical energy as a result of
a self-sustaining spontaneous reaction.
Electrolyte - A substance that can conduct electric current by forming free ions when dissolved or
melted
Grade 11
Intramolecular force - the bond found between the atoms in a molecule (covalent/ionic/metallic)
Covalent bond - the sharing of at least 1 pair of electrons by two non-metal atoms
Ionic bond - the transfer of electrons and subsequent electrostatic attraction
Metallic bond - an electrostatic force of attraction between a positive kernel and a sea of
delocalised electrons
Intermolecular force - the weak forces of attraction that exist between molecules (van der Waal)
London’s forces - found between all molecules due to a temporary shift in the electron cloud
causing a temporary dipole
Dipole-dipole - found between polar molecules due to a difference in electronegativity
Hydrogen bonding - where H is bonded to small, high electronegative atoms which contain at
least 1 lone pair (H -> N, O, F)
Electronegativity - a measure of the tendency of an atom to attract a bonding pair of electrons
Bond energy - the energy required to break a bond between 2 atoms
Polar covalent - a bond formed where there is an unequal sharing of electrons
(different electronegativities)
Exothermic reaction - transforms chemical potential energy into thermal energy (energy release)
Endothermic reaction - transforms thermal energy into chemical potential energy (absorb energy)
Activated complex - a temporary high energy, unstable transition state between the reactants and
the products
Neutralisation - occurs at the point where the acid and base have reacted so that neither is in
excess
Lowrey-bronsted - acid donates a H+ base accepts a H+
Grade 12
Reversible reaction - a reaction where the products can be converted back to reactants
Open system - a system in which matter and energy can be exchanged between the system and
its surroundings
Closed system - a system in which mass is converted inside the system, but energy can enter or
leave the system freely
Reaction rate - the change in concentration per unit time of either a product or a reactant
Le Chatelier's Principle - when an external stress is applied to a system in dynamic equilibrium,
the equilibrium point will change in such a way as to counteract the stress
Equilibrium constant = [products]/[reactants] aA + bB -> cC + dD ( [C]c + [D]d )/( [A]a + [B]b)
Use RICE table for calculations (Ratio, initial, change, end moles)
Oxidation - the loss of electrons (reducing agent) (occurs at the anode)
Reduction - the gain of electrons (oxidising agent) (occurs at the cathode)
Galvanic cells - an electrochemical cell that converts chemical energy to electrical energy as a result of
a self-sustaining spontaneous reaction.
Electrolyte - A substance that can conduct electric current by forming free ions when dissolved or
melted
