- Created by: takeitbackx
- Created on: 08-06-15 19:27
A substance that is made of only one sort of atom is called an element.
The relative electrical charges are as shown:
Name of particle Charge
In an atom, the number of electrons is equal to the number of protons in the nucleus.
Metals lose electrons to form positive ions, whereas non-metals gain electrons to form negative ions.
Limestone, mainly composed of the compound calcium carbonate (CaCO3 ), is quarried and can be used as a building material.
Calcium carbonate can be decomposed by heating (thermal decomposition) to make calcium oxide and carbon dioxide.
Calcium oxide reacts with water to produce calcium hydroxide, which is an alkali that can be used in the neutralisation of acids.
Carbon Dioxide turns limewater cloudy
Limestone is heated with clay to make cement. Cement is mixed with sand to make mortar and with sand and aggregate to make concrete
Ores contain enough metal to make it economical to extract the metal
Metals that are less reactive than carbon can be extracted from their oxides by reduction with carbon, for example iron oxide is reduced in the blast furnace to make iron.
Metals that are more reactive than carbon, such as aluminium, are extracted by electrolysis of molten compounds.
Copper can be extracted from copper-rich ores by heating the ores in a furnace (smelting) and then purified by electrolysis
Copper can be extracted by phytomining, or by bioleaching.
■ phytomining uses plants to absorb metal compounds and that the plants are burned to produce ash that contains the metal compounds
■ bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
Iron from the blast furnace contains about 96% iron. The impurities make it brittle and so it has limited uses, so Most iron is converted into steels, which is an alloy
Transition metals are good conductors of heat and electricity and can be bent or hammered into shape.
Low density and resistance to corrosion make aluminium and titanium useful metals.
■ is a good conductor of electricity and heat
■ can be bent but is hard enough to be used to make pipes or tanks
■ does not react with water
Crude oil is derived from an ancient biomass found in rocks.
Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon atoms only (hydrocarbons). Most of these are saturated hydrocarbons called alkanes
The many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by evaporating the oil and allowing it to condense at a number of different temperatures. This process is fractional distillation.
Most fuels, including coal, contain carbon and/or hydrogen and may contain some sulfur.
The combustion of hydrocarbon fuels releases energy. During combustion the carbon and hydrogen in the fuels are oxidised.
Sulfur dioxide and oxides of nitrogen cause acid rain and solid particles cause global dimming.
Fractions from the distillation of crude oil can be broken down (cracked) to make smaller molecules including unsaturated hydrocarbons such as ethene.
Hydrocarbons can be cracked to produce smaller, more useful molecules.
This process involves heating the hydrocarbons to vaporise them. The vapours are either passed over a hot catalyst or mixed with steam and heated to a very high temperature so that thermal decomposition reactions then occur.
Alkenes react with bromine water, turning it from orange to colourless.
Alkenes can be used to make polymers such as poly(ethene) and poly(propene). In these reactions, many small molecules (monomers) join together to form very large molecules (polymers).
Many polymers are not biodegradable
Ethanol can be produced by hydration of ethene with steam in the presence of a catalyst.
Ethanol can also be produced by fermentation with yeast, using renewable resources.
sugar -----> carbon dioxide + ethanol
Some fruits, seeds and nuts are rich in oils that can be extracted. The plant material is crushed and the oil removed by pressing or in some cases by distillation. Water and other impurities are removed.
Vegetable oils have higher boiling points than water and so can be used to cook foods at higher temperatures than by boiling. This increases the energy released when the food is eaten
Oils do not dissolve in water. They can be used to produce emulsions.
Emulsions are thicker than oil or water
Emulsifiers have hydrophilic and hydrophobic properties.
Hydrophobic TAIL to attach the the oil/ repel from water
Hydrophillic HEAD to attach to the water
Vegetable oils that are unsaturated contain double carbon–carbon bonds. Can detect using bromine water.
Vegetable oils that are unsaturated can be hardened by reacting them with hydrogen in the presence of a nickel catalyst at about 60 °C. This makes them solid at room temperature
Earth and Atmosphere
The atmosphere has been much the same for the last 200 million years
WEGENERS THEORY; Continental Drift wasn't accpeted because scientists once thought that the features of the Earth’s surface were the result of the shrinking of the crust as the Earth cooled down following its formation.
The Earth’s crust and the upper part of the mantle are cracked into a number of large pieces (tectonic plates).
Convection currents within the Earth’s mantle driven by heat released by natural radioactive processes cause the plates to move at relative speeds of a few centimetres per year.
■ about four-fifths (80%) nitrogen
■ about one-fifth (20%) oxygen
■ small proportions of various other gases, including carbon dioxide, water vapour and noble gases
During the first billion years of the Earth’s existence there was intense volcanic activity. This activity released the gases that formed the early atmosphere and water vapour that condensed to form the oceans.
One theory suggests that during this period the Earth’s atmosphere was mainly carbon dioxide and there would have been little or no oxygen gas. Another theory as to how life was formed involves the interaction between hydrocarbons, ammonia and lightning
Plants and algae produced the oxygen that is now in the atmosphere.
Most of the carbon from the carbon dioxide in the air gradually became locked up in sedimentary rocks as carbonates and fossil fuels. Ocean water also has carbon dioxide dissolved into it.
Air is a mixture of gases with different boiling points and can be fractionally distilled to provide a source of raw materials used in a variety of industrial processes.
Argon is UNREACTIVE
Saturated hydrocarbons are the unhealthy ones, hardening ADDS to the unhealthiness
ALKENES will decolourise bromine water - unsaturated as they have a DOUBLE BOND
ALKANES will have a single carbon-carbon bond