Flashcards
Metals
Flashcards do conjunto (25)
- 1What is an ore?Ores are naturally occurring rocks that contain metal or metal compounds in sufficient amounts to make it worthwhile extracting them.
- 2What are most everyday metals called?Most everyday metals are mixtures called alloys.
- 3Earth's CrustThe Earth's crust contains metals and metal compounds such as gold, iron oxide and aluminium oxide, but when found in the Earth these are often mixed with other substances. To become useful, the metals have to be extracted from whatever they are mixed with.
- 4What is a metal ore?A metal ore is a rock containing a metal, or a metal compound, in high enough concentration to make it economic to extract the metal.
- 5The basics of getting an ore out of the ground?Ores are mined. They may need to be concentrated before the metal is extracted and purified.
- 6When are metals produced?Metals are produced when metal oxides are reduced (have their oxygen removed).
- 7Highly Reactive MetalsAluminium, potassium, sodium, calcium and magnesium are extracted by electrolysis.
- 8Low Reactive MetalsIron, zinc, tin and lead may be extracted by reaction with carbon or carbon monoxide.
- 9Other MetalsCopper, silver, gold and platinum are extracted in various ways.
- 10GoldGold, because it is so unreactive, is found as the native metal and not as a compound. It does not need to be chemically extracted from its ore, but chemical reactions may be needed to remove other elements that might contaminate the metal.
- 11Transition MetalsTransition Metal are placed in the large block in the middle of the periodic table. They are good conductors of heat and electricity
they can be hammered or bent into shape easily. - 12IronIron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as haematite contain iron oxide. The oxygen must be removed from the iron oxide to leave the iron behind. Reactions in which oxygen is removed are called reduction reactions.
- 13Iron EquationCarbon is more reactive than iron, so it can push out or displace the iron from iron oxide. Here are the equations for the reaction: iron oxide + carbon → iron + carbon dioxide
2Fe2O3 + 3C → 4Fe + 3CO2 - 14Copper OresSome copper ores are copper-rich – they have a high concentration of copper compounds. Copper can be extracted from these ores by heating them in a furnace, a process called smelting. The copper is then purified using a process called electrolysis.
- 15ElectrolysisDuring electrolysis, positively charged copper (any metal) ions move towards the negative electrode and are deposited as copper (any metal) metal.
- 16PhytominingSome plants absorb copper compounds through their roots. They concentrate these compounds as a result of this. The plants can be burned to produce an ash that contains the copper compounds. This method of extraction is called phytomining.
- 17BioleachingSome bacteria absorb copper compounds. They then produce solutions called leachates, which contain copper compounds. This method of extraction is called bioleaching.
- 18Scrap IronCopper can also be extracted from solutions of copper salts using scrap iron. Iron is more reactive than copper, so it can displace copper from copper salts. For example: iron + copper sulfate → iron sulphate + copper
- 19Aluminium and TitaniumAluminium and titanium are two metals with a low density. This means that they are lightweight for their size. They also have a very thin layer of their oxides on the surface, which stops air and water getting to the metal, so aluminium and titanium resist corrosion.
- 20What are Aluminium and Titanium used for?Aluminium is used for aircraft, trains, overhead power cables, saucepans and cooking foil. Titanium is used for fighter aircraft, artificial hip joints and pipes in nuclear power stations.
- 21Extraction of Aluminium and TitaniumExtracting these metals is very expensive because the processes have many stages and large amounts of energy are needed.
- 22Recycling AluminiumAluminium is extensively recycled because less energy is needed to produce recycled aluminium than to extract aluminium from its ore. Recycling preserves limited resources and requires less energy, so it causes less damage to the environment.
- 23AlloysThe properties of a metal are changed by adding other elements to it. A mixture of two or more elements, where at least one element is a metal, is called an alloy. Alloys contain atoms of different sizes, which distort the regular arrangements of atoms. This makes it more difficult for the layers to slide over each other, so alloys are harder than the pure metal.
- 24Soft MetalsPure copper, gold, iron and aluminium are too soft for many uses. They are mixed with other similar metals to make them harder for everyday use. For example:
Brass, used in electrical fittings, is 70 percent copper and 30 percent zinc.
18 carat gold, used in jewellery, is 75 percent gold and 25 percent copper and other metals.
Duralumin, used in aircraft manufacture, is 96 percent aluminium and 4 percent copper and other metals. - 25IronPure iron is soft and easily shaped because its atoms are arranged in a regular way that lets layers of atoms slide over each other. Pure iron is too soft for many uses.
Iron from the blast furnace is an alloy of about 96 percent iron, with carbon and some other impurities. It is hard, but too brittle for most uses, so most iron from the blast furnace is converted into steel by removing some of the carbon.
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- (Science) FlashCards sobre Metals, criado por elle98 em 16-06-2013.
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