State at room temperature Electrical conductivity C5 – Molecules in the air 5 a day revision Explain why simple molecular substances have low melting and boiling points. Name the main gases in air, give the formula of each one and state their relative proportions. The atoms in molecules are together by covalent bonds. Describe covalent bonding. Why do pure molecular substances not conduct electricity? Boiling point State at room temperature Density Electrical conductivity -218C gas very low does not conduct Use ideas about bonding and forces between molecules to explain the properties of oxygen. @aegilopoides

5 a day revision C5 – Ionic compounds Potassium chloride is an example of a salt found in the sea. Complete the table of results and give reasons for your answers. State two properties of ionic compounds. Describe ionic bonding. Some tests are carried out on a water sample. Use the information in the table to identify the three ions that are present. Test 1. A white precipitate formed when sodium hydroxide was added. It dissolved when excess sodium hydroxide was added. Test 2. Bubbles of gas were given off when nitric acid was added to the sample. When silver nitrate was added a cream precipitate formed. Zinc ions can be detected by adding carbonate ions (CO32-) to form the insoluble compound zinc carbonate (ZnCO3). Work out the charge on the zinc ion and write a balanced ionic equation, including state symbols. @aegilopoides

C5 – Giant molecules and metals 5 a day revision What is the name given to rocks that contain metal minerals. Some metals can be extracted from their ores by heating their metal oxides with carbon. This is called a redox reaction. Describe the two processes that take place using zinc oxide as an example. Carbon dioxide has a simple molecular structure, diamond has a giant covalent structure. Describe the main differences between the two types of structure. Describe and explain 2 properties of diamond. Diamond and graphite are both minerals formed from pure carbon. Explain why graphite can conduct electricity but diamond can’t. You can use a diagram to help explain your answer. @aegilopoides

C5 – Equations, masses and electrolysis 5 a day revision Iron oxide can be heated with charcoal to extract the iron. In one reaction the iron oxide, Fe2O3, reacts with carbon to produce iron and carbon dioxide. Write a balanced symbol equation for this reaction. What is the difference between relative atomic mass and relative formula mass? Lead metal can be extracted from lead oxide (PbO) by heating it with carbon. 2PbO + C  2Pb + CO2 What is the maximum mass of lead that can be extracted from 446g of lead oxide? An electric current is passed through molten potassium chloride. Write ionic equations to help explain what happens at each electrode and name the products that are formed. The diagram shows electricity being passed through molten lead bromide. What will form at each electrode? @aegilopoides

Describe metallic bonding. C5 – Metals and the environment 5 a day revision A mining company can recover 40g of copper ore from every kilogram cuprite (Cu2O ) that is mined. of mined rock. What is the maximum amount of copper metal the company will be able to recover from a kilogram of mined rock? Aluminium is a metal but aluminium oxide is an ionic compound. Aluminium metal and aluminium oxide conduct electricity in different ways. Describe and explain the difference. . Describe metallic bonding. Copper is used to make electrical wiring for homes. Give one reason why copper is a good choice for making electrical wiring and two disadvantages of using copper for this purpose. Copper extraction causes environmental problems due to large amounts of waste rock. Explain why so much waste rock is produced. @aegilopoides