Chapter 6 lands and its resources form3 science
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The document discusses the various minerals found in the Earth's crust, including their composition and properties. It notes that silicate minerals containing oxygen and silicon make up most of the Earth's crust by weight. Key properties of minerals discussed include hardness, reactivity, solubility, and how they are affected by heat. When heated, most metal carbonates decompose to metal oxides and carbon dioxide gas. Metal oxides are generally stable when heated, except for mercury and silver oxides. Metal sulphides typically decompose to metal oxides and sulphur dioxide gas when strongly heated.
Chapter 6 lands and its resources form3 science
- 1. CHAPTER 6 :CHAPTER 6 : LANDLAND AND ITS RESOURCESAND ITS RESOURCES
- 5. 6.1 The Various Minerals Found in6.1 The Various Minerals Found in the Earth’s Crust.the Earth’s Crust. Mineral is natural element or compound found in the Earth’s crust. has a composition and a specific crystalline structure. Examples of minerals are calcite, feldspar, quartz, mica, marble and silicate. Natural elements commonly found in the Earth’s crust are gold, silver, platinum, mercury and arsenic.
- 6. Elements in minerals found in theElements in minerals found in the Earth’s crust.Earth’s crust.
- 7. MineralsMinerals Almost 75% of the weight of a mineral in the Earth’s Crust is made up of oxygen and silicon elements. Thus, silicate minerals which contain oxygen and silicon elements make up the largest amount. Examples of silicate minerals include quartz, feldspar, mica and clay.
- 8. Non-silicate mineralsNon-silicate minerals Minerals that do not contain silicon element are known as non-silicate minerals. Examples of non silicate minerals are calcite, dolomite, magnetite and hematite.
- 9. Non-metallic elementsNon-metallic elements Other non metallic elements such as oxygen, sulphur and carbon usually exist in the form of compounds such as oxides, sulphides and carbonates.
- 10. Elements in natural compoundsElements in natural compounds Oxygen combines with metal chemically form an oxides Metal + oxygen Metal oxide Eg : Iron oxide, copper oxide Carbonates are compounds that contain oxygen, carbon and metals Metal + oxygen + carbon Metal carbonate Eg: sodium carbonate, zinc carbonate Sulphur combines with metals, sulphides are formed Metal + sulphur Metal sulphide Eg : copper sulphide, silver sulphide Metals combine with oxygen and silicon formed a silicates Metal + oxygen + silicon Metal silicate Eg : calcium silicate, and magnesium silicate
- 11. Properties of mineralsProperties of minerals
- 12. HardnessHardness Hardness of mineral refers to the resistance offered by the mineral on being scratched. The hardness of a mineral is measured in Moths unit. Most minerals are hard. These minerals can only be scratched by hard objects such as knives. Nevertheless, hard minerals can scratch softer minerals. All minerals made up of carbonate, oxide and sulphide compounds are hard. Diamond is the hardest mineral while talc is the softest mineral.
- 13. Reactivity and Solubility in waterReactivity and Solubility in waterReactivity and Solubility in waterReactivity and Solubility in water Natural elements are non-reactive elements These elements tend to remain as elements without combining with any other substances All minerals of metal oxides, sulphides and carbonates are insoluble in water, except minerals of metallic potassium and sodium compounds.
- 14. Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects. i. Action of Heat on Metal Carbonates All metal carbonates decompose when heated, except potassium carbonate and sodium carbonate because both the metal carbonates are very stable. The heating of metal carbonates form metal oxides and carbon dioxide gas. Metal carbonates metal oxide + carbon dioxide Eg : calcium carbonates calcium oxide + carbon dioxide Zinc carbonates Metal carbonates metal oxide + carbon dioxide Eg : calcium carbonates calcium oxide + carbon dioxide Zinc carbonates
- 15. Carbon dioxide gas released can beCarbon dioxide gas released can be tested with:tested with: i. Turn lime water milky ii. extinguished burning splinter iii. changes red bicarbonate indicator to yellow Glowing splinter
- 16. ii. Action of Heat on Metal oxides Most metal oxides are stable and do not decompose when heated. Nevertheless, mercury oxide and argentums oxide are exceptions. Both these metal oxides will decompose into oxygen gas and their original metal when heated. Mercury oxides mercury + oxygen Argentums oxides argentum + oxygen *Oxygen gas released can be tested with; i. the glowing splinter will burn brightly Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects.
- 17. iii. Action of Heat on Metal Sulphides Most metal sulphides will decompose when heated strongly to form metal oxides and produce sulphur dioxide gas. Metal sulphides metal oxide + sulphur dioxide Eg : iron sulphides iron oxide + sulphur dioxide Zinc Sulphides Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects.Reaction to heat and its effects.
- 18. Sulphur dioxide gas released is acidic, has a pungent smell and; i. bleaches acidic purple potassium manganate (VII) colourless ii. converts orange acidic potassium dichromate (VI) to green. sulphur dioxide gas released can besulphur dioxide gas released can be tested with:tested with: