The fundamental ideas in chemistry
- The three subatomic particles are protons, electrons and neutrons.
- 2 electrons fill the inner shell, 8 fill the rest of the shells.
- Elements in the same group of the periodic table all have the same number of electrons in their outer orbitals.
- To calculate the number of neurtons in an atom you should take the number of protons form the mass number (mass no. - protons).
- When atoms bond, they gain/lose/share electrons so that they end up with a full outer shell.
- Covalent bonding involves the sharing of electrons. It happends between non-metals (of the same atom-element, 2 different atoms, or a compound), in order for the atom to have a full outer shell.
- Ionic bonding involves electrons been given from one atom to another. It happens between non-metals and metals, in order for the atom to have a full outer shell.
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Rocks and building materials
- The formula of limestone is CaCO3.
- The limestone cycle: 1.Limestone/Calcium Carbonate (CaCO3) [heated strongly] 2.Quicklime/Calcium Oxide (CaO) [2-3 drops of water] 3.Slaked Lime/Calcium Hydroxide (Ca(OH)2) [dissolve it in water] 4. Lime Water/Calcium Hydroxide Solution (Ca(OH)2) [carbon dioxide bubbles]
- Advantages of limestone quarrying in a National Park is that it creates many jobs for unemployed, there is huge demand for the materials quarried, therefore if we quarry there will be more material to supply/sell.
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Metals and their uses
- An ore is a material that conatins metals in such quantities that makes it worth mining for.
- Metals above carbon in the reactivity series are extracted from their ores by the method of electrolysis (the breaking down of a compound uisng electricity).
- Electrolysis is expensive because it is needed for the breaking down of the compound.
- An alloy is a metal made from two combined metallic elements.
- Titanium is a useful metal because it resists corrosion (lasts a very long time) , it has a very high melting point, it is light and also strong- this makes it very useful as an a airplane engine or an artificial joint. However, electrolysis must be used to extract it.
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Fuels from crude oil
- A hydrocarbon is a compound made from hydrogen and carbon.
- Crude oil is separated by a process called fractional distillation.
- In hydrocarbons, all the carbon atoms have 4 chemical bonds.
- The gas that causes acid rain is sulphur dioxide.
- When a hydrocarbon burns, the products are always water and carbon dioxide.
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Products from oil
- Long hydrocarbons are cracked because the products (shorter hydrocarbons) are more useful, e.g aviation fuel.
- Cracking method: 1.Place wool soaked in hyrdocarbon in the end of a boiling tube, alongside broken pot. 2.Put a delivery tube in the end of the boiling tube. 3.Put the end of the boiling tube into a beaker full of water. 4.Begin to heat the end od teh boiling tube with a bunsen burner. 5.Collect the gas bubbles with a testube- place it upside down, just above the end of the delivery tube in the water. 6.Place a bung in the end of the testube collecting the gas once satisfied with the amount collected.
- Alkenes are unsaturated, therefoer they conatine a double bond to the carbon (betwenn hyrdogen and carbon)
- Polymerisation is a chemical process that combines several monomers to form a polymer(ic)compound.
- Ethene is turned into ethanol by fermentaion.
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- Methods of extractig oils from plants are crushing and pressing the plant, or by dissolving in a solvent- once the oil is dissolved, the solvent is removed by distillation, and impurities such as water are also removed, to leave pure oil.
- Oils are hardened using hydrogenation- adding hydrogen to the solition at about 60 degrees centigrade
- To test for unsaturation in an oil you can see if it is liquid at room temperature, as most are.
- The most common use of plant oils is in food. You can also use bromine water- it becomes colourless when in an unsaturated solution and if it stays the same colour then it is saturated.
- An emulsifier is a substance that stops the oil and water from separating into layers.
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Earth and atmosphere
- The layers of the earth are: the crust, the mantle, the outer core and the inner core.
- Rock formations and volcanoes occur when tectonic plates meet.
- Before Alfred Wegener, scientists thought that continents were formed as the Earth cooled.
- The main gases in the atmosphere are Nitrogen, Carbon dioxide, Argon and Oxygen.
- Carbon dioxide in the atmosphere has decreased over the past four billion years, because plants use it in photosynthesis and it is/was absorbed into the oceans.
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