These comprehensive RBSE Class 10 Science Notes Chapter 3 Metals and Non-metals will give a brief overview of all the concepts.
RBSE Class 10 Science Chapter 3 Notes Metals and Non-metals
→ Elements can be classified as metals or non-metals on the basis of their properties.
→ Metals are ductile, malleable, lustrous and are good conductors of heat and electricity. Metals are sonorous also.
→ Metals are solids at room temperature, except mercury which is liquid at room temperature.
→ Metals are generally hard but sodium, potassium, etc. metals are soft.
→ Metallic lustre-Metals, in their pure state, have a shining surface. This property is called metallic lustre.
→ Malleability-Metals can be beaten into thin sheets. This property is called malleability.
→ Ductility-The ability of metals to be drawn into thin wires is called ductility.
→ The malleability of gold and silver is maximum and gold is most ductile metal.
→ Silver and copper are good conductors of heat while lead and mercury are bad conductors of heat.
→ Metals are electropositive element because they form positive ions by losing electrons to non-metals.
→ Alkali metals like lithium, sodium, potassium, are so soft that they can be cut with a knife.
→ Non-metals have properties opposite to that of metals. They are neither malleable nor ductile. Non-metals are bad conductors of heat and electricity, except graphite, which conducts electricity.
→ Non-metals are electronegative elements because they form negatively charged ions by gaining electrons by the reaction with metals.
→ The numbers of non-metals are less than metals.
→ Non-metals are generally solid or gas while bromine is a non metal which is liquid.
→ The melting points and boiling points of metals are high but the melting points of Galium and Caesium are very low.
→ Iodine is lustrous although it is non-metal.
→ Allotropes Different forms of an element having different properties are called Allotropes. Example-Graphite and Diamond are allotropes of carbon.
→ Metals combine with oxygen to form basic oxides but aluminium oxide and zinc oxide show the properties of both basic as well as acidic oxides so these oxides are known as amphoteric oxides.
→ Most metal oxides are insoluble in water but some of these dissolve in water to form alkalis, e.g., Sodium oxide.
→ Non-metals form oxides which are either acidic or neutral.
→ At normal temperature a layer of oxide is formed on the surface of metals like Mg, Al, Zn and Pb which protects these metals from further oxidation.
→ Anodising is a process of forming a thick oxide layer of aluminium.
→ Different metals have different reactivities with water and dilute acids.
→ Reactivity Series is a list of metals arranged in order of their decreasing activities.
→ Metals above hydrogen in the reactivity series can displaces hydrogen from dilute acids.
→ Non-metals do not displace hydrogen from dilute acids. They react with hydrogen to form hydrides.
→ A more reactive metal displaces a less reactive metal from its salt solution.
→ H2 gas is not liberated when metals reacts with Nitric acid (HNO3) because HNO3 is a strong oxidising agent, it oxidises the H2 produced to water and itself get reduced to any of the nitrogen oxides.
→ The compound formed by transfer of electrons, from a metal to a non-metal are known as ionic compounds or electrovalent compounds.
→ Ionic compounds are solid, hard and brittle. Melting points and boiling points of these are high.
→ Ionic compounds are soluble in water but insoluble in solvents like kerosene, petrol etc.
→ Ionic compounds conducts electricity in solution and molten state.
→ Metals are found in nature as free state or in the form of their compounds.
→ Mineral-The elements or compounds, which found naturally in the earth’s crust are called minerals.
→ Ore-The mineral which contain a very high percentage of a particular metal and extraction of metal is convenient and economically profitable is called ores.
→ Metallurgy-The extraction of metals from their ores and then refining them for use is known as metallurgy.
→ Gold, Silver, Platinum and Copper are found in free state.
→ Ores mined from the earth are usually contaminated with large amounts of impurities such as soil, sand, etc., called gangue.
→ Enrichment of Ore – The removal of sand, gravel, etc. (Gaunge) from ore is called enrichment of ores.
→ Calcination – The process of heating the carbonate and Hydrated oxide ore in presence of limited air to convert it into oxide is called calcination.
→ Roasting – The process of heating the sulphide ore in presence of excess air at high temperature to convert it into oxide is called roasting.
→ Most common method used for the purification of metals is electrolytic refining.
→ Alloy – A homogeneous mixture of two or more metals or a metal and a non-metal is called alloy.
→ Corrosion – The surface of some metals, such as iron, is corroded when they are exposed to moist air for a long period of time. This process is called corrosion.