Representing Reactions

Key Issues

Titles

Chapters

• Atoms and symbols are used to represent and explain what is happening to the substances in chemical reactions
• Atoms can be represented with a mass number, an atomic number and the element's chemical symbol
• Atoms of each element are represented by a chemical symbol, e.g. O represents an atom of oxygen, Na represents an atom of sodium
• Calculation of relative formula mass
• Calculation of relative formula masses
• Calculations
• Calculations relating to moles will be limited to use of the relationship: mass(m) = number of moles(n) × relative molecular (atomic) mass (RMM or RAM)
• carry out calculations involving reaction masses from given balanced equations
• Chemical Reactions
• Chemical Symbols
• Concentrations of chemicals in solution may be given in moles per litre if this is appropriate, e.g. in work relating to rates of reaction
• construct simple word equations to describe the range of reactions covered in this specification
• describe the formation of hydrogen chloride and water by the use of the 'dot and cross' model
• describe the formation of sodium chloride and magnesium oxide by the use of the 'dot and cross' model
• Determination of empirical formulae
• Determination of formulae from reacting masses
• Even though no atoms are gained or lost in a chemical reaction, it is not always possible to obtain the calculated amount of a product
• Formulae of elements and simple compounds
• Formulae of elements and simple compounds
• give symbolic representations for some elements and deduce the formulae of simple compounds, limited to elements both of whose valencies in the compound can be established from their positions in the Periodic Table and those groups (hydroxide, sulphate,
• given suitable information, interpret and construct symbol equations to describe named reactions
• interpret data presented in a variety of forms (tables, graphs, databases, prose) to find the physical properties of materials
• interpret simple data presented in a variety of forms (tables, graphs, databases, prose) to find the physical properties of materials
• It is important for sustainable development and for economical reasons to use reactions with high atom economy
• match up formulae and names of compounds
• Neutralisation
• recall and use the formulae of compounds to write balanced symbol equations
• recognise and use symbols for common elements
• recognise reactants and products in a symbol equation
• Relative Formula Mass
• represent chemical reactions by balanced symbolic equations
• Representing Atoms
• Simple balanced equations
• The amount of a product obtained is known as the yield. When compared with the maximum theoretical amount as a percentage, it is called the percentage yield
• The Atom Economy
• The atom economy (atom utilisation) is a measure of the amount of starting materials that end up as useful products
• The Formula of a Compound
• The formula of a compound shows the number and type of atoms that are joined together to make the compound
• The masses of reactants and products can be calculated from balanced symbol equations
• The percentage of an element in a compound can be calculated from the relative mass of the element in the formula and the relative formula mass of the compound
• The relative formula mass of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula
• The relative formula mass of a substance, in grams, is known as one mole of that substance
• The relative masses of protons, neutrons and electrons are proton 1, neutron 1, electron very small
• The Yield of a Chemical Reaction
• Thermal decomposition
• This is because the reaction may not go to completion because it is reversible, some of the product may be lost when it is separated from the reaction mixture or some of the reactants may react in ways different to the expected reaction
• understand that one mole of different substances contains equal numbers of specified particles
• understand the term concentration of a solution expressed in moles per litre (mol/dm3)
• use chemical names for simple compounds
• Use of calcium carbonate to manufacture glass, cement and iron
• Use of calcium oxide and hydroxide to neutralise soil acidity
• Use of chemical equations to calculate reacting masses
• Use of state symbols
• use relative formula mass to determine the number of moles present in a given mass of material
• use state symbols (s, l, g and aq)
• Using equations to calculate the masses of reactants and products
• Word equations
• Word equations and simple balanced equations
• write ionic equations, e.g. to describe electrolysis processes
• write word and symbol equations to show how atoms are rearranged in the chemical reactions in this specification
• Writing balanced equations including ionic equations and those in electrolytic cells
• Writing balanced equations including ionic equations and those occurring in electrolytic cells
• Writing balanced equations including those for reactions at electrodes
• Writing simple balanced equations with state symbols