Chemistry_Grade_10-12 (1).pdf

A potassium nitrate b sodium iodide c barium sulphate

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(a) potassium nitrate (b) sodium iodide (c) barium sulphate (d) nitrogen dioxide (e) sodium monosulphate 4. Refer to the diagram below, showing sodium chloride and water, and then answer the questions that follow. (a) What is the chemical formula for water? (b) What is the chemical formula for sodium chloride? (c) Label the water and sodium chloride in the diagram. (d) Which of the following statements most accurately describes the picture? i. The picture shows a mixture of an element and a compound ii. The picture shows a mixture of two compounds iii. The picture shows two compounds that have been chemically bonded to each other 5. What is the formula of this molecule? H C C O H H H H H A C 6 H 2 O B C 2 H 6 O C 2C6HO D 2 CH 6 O 12
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CHAPTER 1. CLASSIFICATION OF MATTER - GRADE 10 1.4 1.4 Metals, Semi-metals and Non-metals The elements in the Periodic Table can also be divided according to whether they are metals , semi-metals or non-metals . On the right hand side of the Periodic Table is a dark ’zigzag’ line. This line separates all the elements that are metals from those that are non-metals. Metals are found on the left of the line, and non-metals are those on the right. Metals, semi-metals and non-metals all have their own specific properties. 1.4.1 Metals Examples of metals include copper (Cu), zinc (Zn), gold (Au) and silver (Ag). On the Periodic Table, the metals are on the left of the zig-zag line. There are a large number of elements that are metals. The following are some of the properties of metals: Thermal conductors Metals are good conductors of heat and are therefore used in cooking utensils such as pots and pans. Electrical conductors Metals are good conductors of electricity, and are therefore used in electrical conducting wires. Shiny metallic lustre Metals have a characteristic shiny appearance and are often used to make jewellery. Malleable This means that they can be bent into shape without breaking. Ductile Metals can stretched into thin wires such as copper, which can then be used to conduct electricity. Melting point Metals usually have a high melting point and can therefore be used to make cooking pots and other equipment that needs to become very hot, without being damaged. You can see how the properties of metals make them very useful in certain applications. Activity :: Group Work : Looking at metals 1. Collect a number of metal items from your home or school. Some examples are listed below: hammer electrical wiring cooking pots jewellery burglar bars coins 2. In groups of 3-4, combine your collection of metal objects. 3. What is the function of each of these objects? 4. Discuss why you think metal was used to make each object. You should consider the properties of metals when you answer this question.
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