Metals and Non-metals PDF 2024-25
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Uploaded by JudiciousTroll
2024
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Summary
This document is about the general properties of ionic compounds, including their physical nature, melting and boiling points, solubility, and conduction of electricity. It also discusses questions like the electron-dot structures of sodium, oxygen, and magnesium, the formation of Na2O and MgO through the transfer of electrons, the ions present in these compounds, and why ionic compounds have high melting points. This is followed by an introduction on the occurrence of metals in the earth's crust and minerals. Finally, the discussion moves to how metals are extracted from their ores, and some metals are found in the earth's crust in the free state. The last few lines of the document mention the activity series and the least reactive metals.
Full Transcript
You may have observed the following general properties for ionic compounds— (i) Physical nature: Ionic compounds are solids and are somewhat hard because of the strong force of attraction between the positive and negative ions. These compounds are generally brittle and...
You may have observed the following general properties for ionic compounds— (i) Physical nature: Ionic compounds are solids and are somewhat hard because of the strong force of attraction between the positive and negative ions. These compounds are generally brittle and break into pieces when pressure is applied. (ii) Melting and Boiling points: Ionic compounds have high melting and boiling points (see Table 3.4). This is because a considerable amount of energy is required to break the strong inter-ionic attraction. (iii) Solubility: Electrovalent compounds are generally soluble in water and insoluble in solvents such as kerosene, petrol, etc. (iv) Conduction of Electricity: The conduction of electricity through a solution involves the movement of charged particles. A solution of an ionic compound in water contains ions, which move to the opposite electrodes when electricity is passed through the solution. Ionic compounds in the solid state do not conduct electricity because movement of ions in the solid is not possible due to their rigid structure. But ionic compounds conduct electricity in the molten state. This is possible in the molten state since the elecrostatic forces of attraction between the oppositely charged ions are overcome due to the heat. Thus, the ions move freely and conduct electricity. Q U E S T I O N S 1. (i) Write the electr on-dot structures for sodium, oxygen and ? magnesium. (ii) Show the formation of Na2O and MgO by the transfer of electrons. (iii) What are the ions present in these compounds? 2. Why do ionic compounds have high melting points? 3. 4 OCCURRENCE OF MET METALS ALS The earth’s crust is the major source of metals. Seawater also contains some soluble salts such as sodium chloride, magnesium chloride, etc. The elements or compounds, which occur naturally in the earth’s crust, are known as minerals. At some places, minerals contain a very high percentage of a particular metal and the metal can be profitably extracted from it. These minerals are called ores. 3.4.1 Extraction of Metals You have learnt about the reactivity series of metals. Having this knowledge, you can easily understand how a metal is extracted from its ore. Some metals are found in the earth’s crust in the free state. Some are found in the form of their compounds. The metals at the bottom of the activity series are the least reactive. They are often found in a free Metals and Non-metals 49 2024-25
