Science F3 Chap 6 Land and It's Resources

F3 Science Chapter 6

Land and Its Resources

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Minerals

•Rocks – made up of minerals•Minerals – solid elements/compounds

found naturally•Example?

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Gold

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Quartz 石英 (silicon dioxide)

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Limestone 石灰石 (calcium carbonate)

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Minerals

•Most minerals, are found as natural compounds in the form of oxides, sulphides, carbonates, and silicates.

•Although there are about 3000 types of minerals in the Earth’s crust, only 25 types are present in large quantities

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Identifying the elements in natural compounds•Minerals found as natural compound ---

metallic elements combined with non-metallic elements

•Example: Haematite 赤铁矿

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Elements present in minerals that are found as natural compoundsNatural compound

Mineral Elements

Oxide Haematite Iron, oxygen

Cassiterite Tin, oxygen

Carbonate Calcite Calcium, carbon, oxygen

Malachite Copper, carbon, oxygen

Sulphide Iron pyrite Iron, sulphur

Galena Lead, sulphur

Silicate China clay Aluminium, silicon, oxygen

Calcium silicate Calcium, silicon, oxygen

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Properties of minerals

•Hard•Insoluble•Heating?

▫Most metal oxides are stable, cannot be broken down by heating.

▫But there are exceptions

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When some minerals are heated…1. Metal Suphide

▫Breaks down into a metal oxide and releases sulphur dioxide gas

▫Equation?▫This gas changes the potassium manganate

(VII) solution from purple to colourless

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When some minerals are heated…2. Metal Carbonate

▫Change to their oxides and carbon dioxide when burnt in air.

▫Equation?▫The carbon dioxide gas causes limewater to

turn cloudly

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6.2 Reactions Between Metal and Non-metal•Reaction of metals with oxygen

▫A metal oxide is formed▫Equation?

Metal + oxygen –(heated)--> Metal oxide•Reaction of metals with sulphur

▫A metal sulphide is formed▫Equation?

Metal + Sulphur –(heated)--> Metal sulphide

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Reactions of Metals with O2

Metal Reaction rate

Product of reaction

Magnesium

Very fast Magnesium oxide

Aluminium Very fast Aluminium oxideZinc Fast Zinc oxideIron Fast Iron oxideCopper Slow Copper oxide

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Reactions of Metals with Sulphur, S

Metal Reaction rate

Product of reaction

Magnesium Very fast Magnesium sulphide

Aluminium Very fast Aluminium sulphideZinc Fast Zinc sulphideIron Fast Iron sulphideCopper Slow Copper sulphide

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6.3 Silicon Compounds 硅 , 矽

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6.3 Silicon Compounds 硅 , 矽•Silicon is the second most abundant

element in the Earth’s crust.•Silicon does not exist as a free element in

its natural state, but in compounds•Silicon compounds in the Earth’s crust –

silica, silicates

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Silica 矽石 – silicon dioxide

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Silicates 硅酸盐– silicon, metal, oxygen

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Silicon compounds and their examplesSilicon compound

Example

Silica Sand, quartzSilicate Asbestos, jade, clay,

mica

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Asbestos

Jade

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Clay

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Mica 云母

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Silica and Silicates

•Insoluble in water•Do not react with acid•Do not break down when heated•That’s why they are very stable in the

Earth crust•Hence, not easily eroded, found in large

quantities in the Earth’s crust

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Silica and Silicates

•In industry:▫Manufacture of glass, fiber optic cables,

ceramics

ceramics

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6.4 Calcium compounds

•Calcium carbonate is an important calcium compound

•Consists of calcium, carbon, and oxygen

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Marble

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Animal shell

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Coral

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Calcium Carbonate

•Insoluble in water•Reacts with dilute hydrochloric acid to

produce salt, water and carbon dioxide•Equation?

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Calcium carbonate

•When heated strongly, calcium carbonate changes to calcium oxide (quicklime) and carbon dioxide is released

•Few drops of water are added to calcium oxide, effervescence occur and heat is given off, forming calcium hydroxide

•When more water is added, it dissolves to form calcium hydroxide solution, also known as limewater

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Petroleum

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Petroleum

•Mixture of several hydrocarbons, which consist of hydrogen and carbon only

•Hydrocarbons in petroleum are separated by a process called fractional distillation

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