Key definitions

Essential revision notes/key definitions for OCR AS Chemistry.

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  • Created by: laura
  • Created on: 31-03-10 14:18

Oxidation

Is loss of electrons or an increase in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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Reduction

Is gain of electrons or a decrease in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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A Reducing Agent

is a reagent that reduces (adds an electron to) another species.

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An Oxidation Agent

is a reagent that oxidises (takes an electron from) another species.

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An Oxidation number

is a measure of the number of electrons that an atom used to bond with atoms of another element. Oxidation numbers are derived from a set of rules.

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Water of crystallisation

refers to water molecules that form an essential part of the crystalline structure of a compound.

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Anhydrous

refers to a substance that contains no water molecules.

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Hydrated

Refers to a substance that contains no water molecules.

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An Anion

Is a negalively charged ion.

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A Cation

is a positively charged ion

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A Salt

is any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH4+.

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An Acid

is a species that is a proton donor.

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A Base

is a proton acceptor.

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Stoichiometry

is the molar relationship between the relative quantities of substances taking part in a reaction.

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Oxidation

Is loss of electrons or an increase in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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Reduction

Is gain of electrons or a decrease in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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Concentration

of a solution is the amount of a solute, in mol, dissolved per 1dm3 (1000 cm3) of solution.

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A Reducing Agent

is a reagent that reduces (adds an electron to) another species.

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A Standard Solution

is a solution of known concentration. Standard solutions are normally used in titrations to determine unknown infomation about another substance.

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An Oxidation Agent

is a reagent that oxidises (takes an electron from) another species.

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Reduction

Is gain of electrons or a decrease in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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An Oxidation number

is a measure of the number of electrons that an atom used to bond with atoms of another element. Oxidation numbers are derived from a set of rules.

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A molecule

is a small group of atoms held together by covalent bonds.

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Water of crystallisation

refers to water molecules that form an essential part of the crystalline structure of a compound.

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A Molecular forumla

is the actual number of atoms of each element in a molecule.

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Anhydrous

refers to a substance that contains no water molecules.

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Empirical Formula

is the simplest whole-number ratio of atoms of each element present in a compound.

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Molar Volume

is the volume per mole of a gas. The units of molar volume are dm3 mol-1. At room temperature and pressure, the molar volume is approximately 24.0 dm3 mol -1.

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Molar Mass, (M or Mr)

is the mass per mole of a substance. The units of molar mass are g mol-1.

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An Anion

Is a negalively charged ion.

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The Avogadros Constant, (NA)

is the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol-1)

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A Cation

is a positively charged ion

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Amount of substance

is the quantity whose unit is the mole. Chemists use 'amount of substance' as a means of countine atoms.

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Oxidation

Is loss of electrons or an increase in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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A Salt

is any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH4+.

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Reduction

Is gain of electrons or a decrease in oxidation number.

(For oxidation and reduction remember OILRIG: Oxidation is loss, Reduction is gain)

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An Acid

is a species that is a proton donor.

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A mole

is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.

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A Reducing Agent

is a reagent that reduces (adds an electron to) another species.

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A Base

is a proton acceptor.

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An Oxidation Agent

is a reagent that oxidises (takes an electron from) another species.

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Stoichiometry

is the molar relationship between the relative quantities of substances taking part in a reaction.

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An Oxidation number

is a measure of the number of electrons that an atom used to bond with atoms of another element. Oxidation numbers are derived from a set of rules.

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A Species

is a type of partical that takes place in a chemical reaction.

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Water of crystallisation

refers to water molecules that form an essential part of the crystalline structure of a compound.

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Concentration

of a solution is the amount of a solute, in mol, dissolved per 1dm3 (1000 cm3) of solution.

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Anhydrous

refers to a substance that contains no water molecules.

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A Standard Solution

is a solution of known concentration. Standard solutions are normally used in titrations to determine unknown infomation about another substance.

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Hydrated

Refers to a substance that contains no water molecules.

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Molar Volume

is the volume per mole of a gas. The units of molar volume are dm3 mol-1. At room temperature and pressure, the molar volume is approximately 24.0 dm3 mol -1.

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An Anion

Is a negalively charged ion.

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A molecule

is a small group of atoms held together by covalent bonds.

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A Cation

is a positively charged ion

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A Molecular forumla

is the actual number of atoms of each element in a molecule.

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A Salt

is any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH4+.

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Empirical Formula

is the simplest whole-number ratio of atoms of each element present in a compound.

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A Reducing Agent

is a reagent that reduces (adds an electron to) another species.

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Molar Mass, (M or Mr)

is the mass per mole of a substance. The units of molar mass are g mol-1.

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A Base

is a proton acceptor.

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The Avogadros Constant, (NA)

is the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol-1)

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Stoichiometry

is the molar relationship between the relative quantities of substances taking part in a reaction.

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Amount of substance

is the quantity whose unit is the mole. Chemists use 'amount of substance' as a means of countine atoms.

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A Species

is a type of partical that takes place in a chemical reaction.

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A mole

is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.

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Concentration

of a solution is the amount of a solute, in mol, dissolved per 1dm3 (1000 cm3) of solution.

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An ion

is a positively or negatively charged atom or (covalently bonded) group of atoms (a molecular ion).

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A Standard Solution

is a solution of known concentration. Standard solutions are normally used in titrations to determine unknown infomation about another substance.

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Molar Volume

is the volume per mole of a gas. The units of molar volume are dm3 mol-1. At room temperature and pressure, the molar volume is approximately 24.0 dm3 mol -1.

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A molecule

is a small group of atoms held together by covalent bonds.

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Hydrated

Refers to a substance that contains no water molecules.

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Empirical Formula

is the simplest whole-number ratio of atoms of each element present in a compound.

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Molar Mass, (M or Mr)

is the mass per mole of a substance. The units of molar mass are g mol-1.

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The Avogadros Constant, (NA)

is the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol-1)

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Amount of substance

is the quantity whose unit is the mole. Chemists use 'amount of substance' as a means of countine atoms.

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A mole

is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.

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An ion

is a positively or negatively charged atom or (covalently bonded) group of atoms (a molecular ion).

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