F3 Science Chapter 6
Land and Its Resources
http://xinhuicafe.wordpress.com Last update: 17/7/2010
Minerals
•Rocks – made up of minerals•Minerals – solid elements/compounds
found naturally•Example?
http://xinhuicafe.wordpress.com
Gold
http://xinhuicafe.wordpress.com
Quartz 石英 (silicon dioxide)
http://xinhuicafe.wordpress.com
Limestone 石灰石 (calcium carbonate)
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
Identifying the elements in natural compounds•Minerals found as natural compound ---
metallic elements combined with non-metallic elements
•Example: Haematite 赤铁矿
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
Properties of minerals
•Hard•Insoluble•Heating?
▫Most metal oxides are stable, cannot be broken down by heating.
▫But there are exceptions
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
6.3 Silicon Compounds 硅 , 矽
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
Silica 矽石 – silicon dioxide
http://xinhuicafe.wordpress.com
Silicates 硅酸盐– silicon, metal, oxygen
http://xinhuicafe.wordpress.com
Silicon compounds and their examplesSilicon compound
Example
Silica Sand, quartzSilicate Asbestos, jade, clay,
mica
http://xinhuicafe.wordpress.com
Asbestos
Jade
http://xinhuicafe.wordpress.com
Clay
http://xinhuicafe.wordpress.com
Mica 云母
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
Silica and Silicates
•In industry:▫Manufacture of glass, fiber optic cables,
ceramics
ceramics
http://xinhuicafe.wordpress.com
6.4 Calcium compounds
•Calcium carbonate is an important calcium compound
•Consists of calcium, carbon, and oxygen
http://xinhuicafe.wordpress.com
Marble
http://xinhuicafe.wordpress.com
Animal shell
http://xinhuicafe.wordpress.com
Coral
http://xinhuicafe.wordpress.com
Calcium Carbonate
•Insoluble in water•Reacts with dilute hydrochloric acid to
produce salt, water and carbon dioxide•Equation?
http://xinhuicafe.wordpress.com
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
http://xinhuicafe.wordpress.com
Petroleum
http://xinhuicafe.wordpress.com
Petroleum
•Mixture of several hydrocarbons, which consist of hydrogen and carbon only
•Hydrocarbons in petroleum are separated by a process called fractional distillation
http://xinhuicafe.wordpress.com
http://xinhuicafe.wordpress.com