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Terms in this set (45)
How many electrons do all of the group 1 elements have in their outer shell?
How many electrons do all of the group 7 elements have in their outer shell?
Why do atoms have no overall charge?
In an atom there are always an equal number of protons and electrons which results in no net electrical charge.
Describe the bonding in sodium chloride.
Describe the bonding in water.
Why are group 8 elements unreactive?
because they have a full outer shell, they are noble gases
Where do we get metals from?
Metals are found in the Earth's crust. Unreactive metals such as gold are found in the Earth as the metal itself, but most metals are found as compounds that require chemical reactions to extract the metal.
What is an ore?
Ores are rocks that contain enough metal to make it economic viable to extract the metal from them.
Most ores have to be processed before metal is extracted from them. What has to be done to the ore?
Ores are mined and may be concentrated before the metal is extracted and purified.
What are the environmental issues associated with mining ores.
a lot of electricity and energy used
How are methods of extracting metals linked to the reactivity series? Give examples.
Metals above carbon in the reactivity series must be extracted using electrolysis, Metals less reactive than carbon can be extracted from their ores by reduction, Copper, silver, gold and platinum can occur native and do not need to be extracted. Sometimes copper needs to be extracted from an ore.
Metals are extracted from their oxides by reduction. What is reduction?
REDLOX - Reduction is the loss of oxygen from a compound in a chemical reaction.
what is the symbol equation for the reaction reaction that takes place in a blast furnace (iron (III) oxide is Fe2O3)?
Fe2O3 + 3CO → 2Fe + 3CO2.
How is iron ore reduced?
we extract iron from the iron ore by reducing it using carbon in a blast furnace
Why is iron from a blast furnace not very useful and why?
pure iron is too soft for it to be useful
How is iron from a blast furnace changed to make it more useful?
Carefully controlled quantities of carbon and other elements are added to iron to make alloys of steel with different properties.
An alloy is a material composed of two or more metals or a metal and a nonmetal.
Why are alloys useful?
Alloys are useful because they have so many different uses and there are many different types. If you alloy pure iron with carbon you can create steel, which is much stronger and more useful than iron. Also: Titanium aluminum, it is lighter, much stronger, and corrosion resistant.
It is used in making fighter.
What are the following made from, what are they used for and why: Low-carbon steel, High-carbon steel, Stainless steel
low carbon steel - iron alloyed with o.25% carbon, used for car body panels as its easily shaped.
High carbon steel - iron alloyed with up to 2.5% carbon and used for cutting tools as its hard.
stainless steel - iron alloyed with chromium and nickel, used for cutlery as it is resistant to corrosion.
What is the main disadvantage of using iron and steel for construction?
Heavy and thus expensive to transport, susceptible to corrosion- steel bridges must be painted continuously, particularly in a salty environment.
Has a high expansion rate in changing temperatures, and this must be allowed for in the engineering. In conditions of repeated stress and changing temperatures, can suffer fatigue and cracks, and more corrosion.
Energy intensive to produce.
Explain why copper, aluminum and gold are rarely used in their pure form and are commonly found mixed with small amounts of other elements.
they are alloyed with other metals to make them harder and more useful.
How is aluminium extracted and why is this method used?
electrolysis because it is more reactive that carbon so it cannot be displaced by it
Describe the economic issues with extracting aluminium.
Aluminium is the most abundant metal on Earth. Despite this, it is expensive, largely because of the amount of electricity used up in the extraction process.
Describe the environmental issues with extracting aluminium.
it uses a lot of energy and non-renewable resources -uses lots of electricity
How is titanium extracted and why is this method used?
Titanium forms titanium carbide with carbon, which makes the metal brittle, this method is used because titanium is less reactive than carbon so it can be displaced.
Describe the economic issues with extracting titanium.
Titanium extraction is expensive because the process involves several stages and a lot of energy.
Describe the environmental issues with extracting titanium.
it uses a lot of energy (which uses up non-renewable resources) because as well as the displacement, the metals used to displace titanium have to undergo electrolysis beforehand.
Write the word and symbol equation for smelting -heating copper sulfide (I) in air. (Extracting copper from copper rich ores)
copper(I) sulfide + oxygen --> copper + sulfur dioxide
What are the main types of steel?
low carbon steels -easily shaped-used for car body panels
high carbon steels- very hard- used for cutting tools
stainless steel-resistant to corrosion-used for cutlery
Why are aluminium and titanium so useful?
resistant to corrosion
Why does it cost so much to extract aluminum and titanium?
Aluminium and titanium are expensive because extracting them from their ores involves many stages and requires lots of energy
Uses of aluminium?
drinks cans, cooking foil, airplanes, bicycles, saucepans
uses of titanium?
high-performance aircraft (because strength and low density), parts of jet engines (because keeps strength at high temperatures) , replacement hip joints (low density, strength, resistant to corrosion)
How is copper obtained from copper-rich ores?
extracting by smelting copper-rich ores, although our limited supplies of ores are becoming more scarce.
What methods can be used to obtain copper from low-grade ores?
copper can be extracted from copper solutions by electrolysis or by displacement using scrap iron. Electrolysis is also used to purify impure copper, e.g. from smelting. scientists are developing ways to extract copper that use low-grade copper ores. Bacteria are used in bioleaching and plants in phytomining.
How is copper purified?
electrolysis is used to purify impure copper eg from smelting
What is phytomining?
in phytomining, plants can absorb copper ions from low-grade copper ore as the grow. This could be on slag heaps of previously discarded waste from the processing of copper-rich ores. Then the plants are burned and the metals can be extracted from ash. The copper ions can be "leached" (dissolved) from the ash by adding sulphuric acid. This makes a solution of copper sulphate. Then we can use displacement by scrap iron and electrolysis to extract pure copper.
What is bioleaching?
In bioleaching, bacteria feed on low-grade metal ores. By a combination of biological and chemical processes, we can get a solution of copper ions (called a "leachate") from waste copper ore. Once again, we can use scrap iron and electrolysis to extract the copper from the leachate. 20% of copper comes from bioleaching - likely to increase as copper-rich ores run out. Its a very slow process -scientists trying to speed it up.
What are transition metals and why are they so useful?
transition metals are found in the central block in periodic table. Transition metals have properties that make them useful for building and making things. For example, copper is used in wiring because of its high electrical conductivity.
Why are alloys more useful than pure metals?
copper, gold and aluminium are all alloyed with other metals to make them harder.
What issues arise in exploiting metal ores?
- when ores of aluminium, copper and iron are mined using open cast mining - huge pits that scar the landscape are made, creating noise and dust and destroying the habitats of animals and plants+leave waste rock.- water can be affected as rain drains through exposed ores and slag heaps of waste, ground water can become acidic.- ores must be processed to extract metals, eg, sulphide ores are heated strongly in smelting - sulfur dioxide that escapes into air can cause acid rain
How can plants help to exploit low-grade metal ores?
plants can remove metals from low-grade ores. The metals can be recovered by processing the ash from burning the plants.
Why should we recycle metals?
saves energy and our limited metal ores (and fossil fuels). The pollution from extracting metals is also reduced.
What are the good points in using metals to build structures?
- copper good conductor for wiring; not reactive so can be made into water pipes as well.-lead bent easily so used to seal joints on roofs.-aluminium alloys are corrosion resistant.-steel is strong for girders and scaffolding.
What are the bad points in using metals to build structures?
- iron and steel can rust, severely weakening structures.-exploitation of metal ores to extract metals causes pollution and uses up the Earth's limited resources.
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