Chemistry Definitions Grade 12
1. Know the following polyatomic ions:
Ammonium NH4 +
Chlorate ClO3 -
Ethanoate CH3COOH -
Hydroxide OH -
Nitrate NO3 -
Nitrite NO2 -
Permanganate MNO4 -
Carbonate CO3 2-
Hydrogen carbonate HCO3 -
Sulphate SO4 2-
Hydrogen sulphate HSO4 -
Thiosulfate S2O3 2-
Sulphite SO3 2-
Phosphate PO4 3-
Dichromate Cr2O7 2-
2. Molar mass – the mass in grams of one mole of that substance.
3. Solution – a homogenous mixture of solute and solvent.
4. Solute – the substance that is dissolved in the solution.
5. Solvent – the substance in which another substance is dissolved, forming a
solution.
6. Concentration –the amount of solute per unit volume of solution.
7. 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.
Note that yield is generally expressed as a percentage.
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, 8. Intramolecular bond - a bond which occurs between atoms within molecules.
9. A covalent bond - a sharing of at least one pair of electrons by two non-
metal atoms.
10. Non-polar covalent (pure covalent) - an equal sharing of electrons.
11. Polar covalent - unequal sharing of electrons leading to a dipole forming (as
a result of electronegativity difference).
12. Electronegativity - a measure of the tendency of an atom to attract a
bonding pair of electrons.
13. Ionic bond - a transfer of electrons and subsequent electrostatic attraction
14. Metallic bonding – occurs between a positive kernel and a sea of delocalised
electrons.
15. Intermolecular force – a weak force of attraction between molecules, ions, or
atoms of noble gases.
16. Heat of reaction (ΔH) - the net change of chemical potential energy of the
system.
17. Exothermic reactions – reactions which transform chemical potential energy
into thermal energy.
18. Endothermic reactions – reactions which transform thermal energy into
chemical potential energy.
19. Activation energy – the minimum energy required to start a chemical
reaction OR the energy required to form the activated complex.
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1. Know the following polyatomic ions:
Ammonium NH4 +
Chlorate ClO3 -
Ethanoate CH3COOH -
Hydroxide OH -
Nitrate NO3 -
Nitrite NO2 -
Permanganate MNO4 -
Carbonate CO3 2-
Hydrogen carbonate HCO3 -
Sulphate SO4 2-
Hydrogen sulphate HSO4 -
Thiosulfate S2O3 2-
Sulphite SO3 2-
Phosphate PO4 3-
Dichromate Cr2O7 2-
2. Molar mass – the mass in grams of one mole of that substance.
3. Solution – a homogenous mixture of solute and solvent.
4. Solute – the substance that is dissolved in the solution.
5. Solvent – the substance in which another substance is dissolved, forming a
solution.
6. Concentration –the amount of solute per unit volume of solution.
7. 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.
Note that yield is generally expressed as a percentage.
Page 1 of 11
, 8. Intramolecular bond - a bond which occurs between atoms within molecules.
9. A covalent bond - a sharing of at least one pair of electrons by two non-
metal atoms.
10. Non-polar covalent (pure covalent) - an equal sharing of electrons.
11. Polar covalent - unequal sharing of electrons leading to a dipole forming (as
a result of electronegativity difference).
12. Electronegativity - a measure of the tendency of an atom to attract a
bonding pair of electrons.
13. Ionic bond - a transfer of electrons and subsequent electrostatic attraction
14. Metallic bonding – occurs between a positive kernel and a sea of delocalised
electrons.
15. Intermolecular force – a weak force of attraction between molecules, ions, or
atoms of noble gases.
16. Heat of reaction (ΔH) - the net change of chemical potential energy of the
system.
17. Exothermic reactions – reactions which transform chemical potential energy
into thermal energy.
18. Endothermic reactions – reactions which transform thermal energy into
chemical potential energy.
19. Activation energy – the minimum energy required to start a chemical
reaction OR the energy required to form the activated complex.
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