Chem Definitions

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Molar mass?

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The mass in grams of one mole of that substance.

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A solute?

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The substance that is dissolved in water.

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A solvent?

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The substance in which another substance is dissolved, forming a solution.

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Concentration?

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The nr of moles of solute per unit volume of solution.

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A standard solution?

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Is a solution of known concentration.

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Electronegitivity?

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Is a measure of the tendency of an atom to attract a bonding pair of electrons.

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A covalent bond?

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Is the sharing of at least one pair of electrons by two atoms.

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A non-polar covalent (pure covalent) bond?

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An equal sharing of electrons.

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A polar covalent bond?

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Is unequal sharing of electrons leading to a dipole forming.

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Ionic bonding?

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Is the transfer of electrons and subsequent electrostatic attraction.

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Metallic bonding?

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Is bw a positive kernel and a sea of delocalised electrons.

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An intramolecular bond?

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Is the bond occurring bw atoms within the molecules.

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Intermolecular force?

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Is a weak force of attraction bw molecules or bw atoms of noble gases.

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A hydrocarbon?

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Is a compound containing only carbon and hydrogen atoms.

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Homologous series?

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Is a series of similar compounds which have the same functional group and have the same general formula, where each member differs from a single CH2 unit.

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(Structural) Isomers?

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Are compounds that have the same molecular formula but different structural formulae.

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A functional group?

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Is an atom or a group of atoms that form the centre of chemical activity in the molecule.

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A saturated compound?

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Is a compound in which all of the bonds bw carbon atoms are single bonds.

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Unsaturated compounds?

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Is a compound in which there is atleast one double and/or triple bond bw carbon atoms.

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Heat of reaction (🔺H)

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Is the net change of chemical potential energy of the system.

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Exothermic reaction?

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Are reactions which transfer potential energy to thermal energy.

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Endothermic reaction?

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Are reactions which transfer thermal energy into potential energy.

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Reaction rate?

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Is the change in concentration per unit time of either a reactant or product.

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Activation energy?

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Is the Minimum energy required to start a chamical reaction.

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The activated complex?

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Is an unstable transition state bw the reactant and the products.

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A catalyst?

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Is a substance that ➕ the rate of the reaction but remains unchanged at the end of the reaction.

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Yield?

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Is a measure of the extent of a reaction, generally measure by comparing the amount of product against the amount of product that is possible.

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Le Chatelier's Principle?

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When an external stress is applied to a system in chamical equilibrium, the equilibrium point will change in such a way as to counteract the stress.

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Lowry-Bronsted theory?

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Acid: is a proton (H+ ion) donor.

Base: is a proton (H+ ion) acceptor.

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A strong acid ?

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Is an acid that ionises almost completely in an aqueous solution.

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A strong base?

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Is a base that dissociated almost completely in an aqueous solution.

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A weak acid?

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Is an acid that only ionises partially in an aqueous solution.

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A weak base?

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Is a base that only dissociates partially in an aqueous solution.

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Kw for water?

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At 25 degrees Celsius : Kw = (H30+) (OH-)

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A salt?

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Is a substance in which hydrogen of an acid has been replaced by a cation.

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Neutralization?

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Is the point where an acid and base reacted so neither is in excess.

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Hydrolysis of salt?

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Is a reaction with water where water itself is decomposed.

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Oxidation?

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Is the loss of electrons.

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Reduction?

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Is the gain of electrons.

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An oxidizing agent?

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Is a substance that accepts electrons.

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A reducing agent?

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Is a substance that donates electrons.

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An anode?

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Is the electrode where oxidation takes place.

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A cathode?

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Is the electrode where reduction takes place.