Pregunta | Respuesta |
How many elements are there? | About 100 |
What do the groups contain? | Elements with similar properties. |
What is the symbol for sodium? | Na |
What is in the nucleus of an atom? | Protons and Neutrons |
What orbits the nucleus? | Electrons |
what is the charge of an electron? | -1 |
what is the overall charge of an atom? | zero |
What does the atomic number tell us? | The number of protons. |
What does the mass number tell us? | The sum of protons and neutrons. |
Al has 13 electrons, give its electronic structure. | 2,8,3 |
What is important about elements in the same group? | They have the same number of electrons in the outer shell. |
What is the name for group 0 elements? | Noble gases |
Why are group 0 elements unreactive? | Stable arrangement of electrons. |
What 3 ways do atoms form compounds? | Giving, taking and sharing electrons. |
What bonding is formed between a metal and non-metal? | ionic |
What bonding is formed between non-metals only? | Covalent |
What is important about the mass of a chemical reaction? | The mass stays the same. |
What is the chemical name for limestone? | calcium carbonate CaCO3 |
What is the name for the reaction where limestone is heated? | Thermal decomposition |
What are the 2 products of heating limestone? | calcium oxide + carbon dioxide |
Give 5 carbonates which also decompose. | Mg, Cu, Zn, Ca, Na |
What is the product of reacting calcium oxide and water? | calcium hydroxide |
What is calcium hydroxide used for? | neutralising acid |
What is another name for calcium hydroxide? | Lime water |
What do we get when we react calcium hydroxide with carbon dioxide? | calcium carbonate |
What happens to lime water when you react it with carbon dioxide? | It goes cloudy |
what forms when carbonates react with acid? | carbon dioxide, water and salt |
How do we make cement? | Heat clay and limestone. |
How do we make mortar? | cement and sand |
How do we make concrete? | Cement, sand and aggregate. |
What is an ore? | Rock that contains enough metal to make it economical to extract. |
What happens to an ore? | Mined and concentrated, then extracted and purified. |
Name a metal found in the Earth by itself? | Gold |
How are most metals found? | As compounds |
Which metals are extracted by reduction with carbon? | Metals lower than carbon in the reactivity series |
How are more reactive metals extracted? | Electrolysis of molten compounds. |
What is the disadvantage of electrolysis? | high cost |
What is smelting? | Heating copper rich ores in a furnace. |
What is the problem with copper ores? | Limited supply |
Name 4 other ways of extracting copper. | Phytomining, bioleaching, displacement using scrap iron and electrolysis of copper salts. |
Why is it expensive to extract Al and Ti? | Many stages in the process and large amounts of energy needed. |
Why should we recycle metals? | Save resources, expensive in terms of energy, affects the environment. |
How pure is iron from a blast furnace? | 96% |
why is this impure iron almost useless? | impurities make it brittle. |
What is steel? | An alloy of iron with carbon. |
Give a property of low carbon steel. | Easily shaped. |
Give a property of high carbon steel. | Hard |
Give a property of stainless steel. | Resistant to corrosion. |
Why do we usually make alloys from metals? | To make the harder for everyday use. |
What do we call the elements in the central block of the periodic table? | Transition metals. |
Give three properties of transition metals? | Conduct heat, conduct electricity, can be bent or hammered into shape. |
What do we use copper for? | Electrical wiring and plumbing. |
Why are Al and Ti useful? | Low density and resistant to corrosion. |
What is crude oil? | A mixture of a large number of compounds that contain carbon and hydrogen. |
What is a mixture? | Two or more elements or compounds that are not chemically combined. |
What are hydrocarbons? | Compounds containing only carbon an hydrogen. |
What are saturated compounds called? | Alkanes |
What is the general formula for alkanes? | Cn H2n +2 |
What process separates the compounds in crude oil? | Fractional distilation. |
As the carbon chain increases, what happens to the boiling point? | increases |
As the carbon chain increases what happens to the viscosity? | increases |
As the carbon chain increases, what happens to the flammability? | Decreases. |
What elements do most fuels contain? | Carbon, hydrogen and some sulphur. |
What gases are produced when fuels are burnt? | carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and nitrogen dioxide. |
What happens to the carbon and hydrogen during combustion? | They are oxidised. |
What is the main problem with sulphur dioxides and nitrogen dioxides? | Acidic rain. |
What problem does carbon dioxide cause? | Global warming. |
What problem do solid particles cause? | Global dimming. |
From what do we make biofuels? | biodiesel and ethanol. |
How do we get small hydrocarbons from larger ones? | Cracking |
What is the process of cracking? | Heating the hydrocarbons to vaporise them, then passing over a hot catalyst or mixing with steam at a very high temperature. |
What are the products of cracking? | alkanes and alkenes |
What is the general formula for alkenes? | Cn H2n |
What does = represent in an alkene? | A double bond. |
What do we see when bromine water is added to alkanes? | The bromine water stays orange. |
What do we see when bromine is added to alkenes? | The bromine goes from orange to colourless. |
How are polymers made? | Many small molecules join together to form very large molecules. |
What are the small molecules used to make polymers called? | Monomers |
Give 2 uses of polymers. | Packaging materials, waterproof coating, dental polymers wound dressings, hydrogels, smart materials. |
Why is the disposal of polymers a problem? | polymers are not biodegradable. |
What are new biodegradable plastics made from? | Corn starch |
Give 2 methods of making ethanol. | Reacting ethene with steam with a catalyst, or fermenting sugar with yeast. |
Give the equation for fermentation. | yeast Sugar----> carbon + ethanol dioxide |
From what are vegetable oils extracted? | Nuts, seeds and fruit. |
How is the oil removed? | Plant material crushed, oil pressed out or distilled. |
What is removed during the process? | Water and impurities |
What are vegetable oils important for? | Food and fuel |
Why are oils important? | They provide a lot of energy |
Give an advantage of using oil to cook. | Food cooks faster, different flavour. |
Give a disadvantage of using oil to cook. | More energy is released. |
What is an emulsion? | mix of oil and water which doesn't separate. |
Give 4 uses of emulsions. | Salad dressing, paints, cosmetics and ice cream. |
What does hydrophilic mean? | likes water. |
What does hydrophobic mean? | Dislikes water. |
What do unsaturated molecules contain? | Double carbon=carbon bonds |
What happens to bromine water with unsaturated molecules? | Turns from orange to colourless. |
How do we harden vegetable oils? | Through hydrodgenation. |
Describe the process of hydrogenation. | React vegetable oil with hydrogen, with a nickle catalyst at 60C |
What is hardened vegetable oil? | Margarine |
What are the three sections of the Earth? | Core, mantle, and crust. |
What are the crust and upper mantle cracked into? | tectonic plates. |
How fast do tectonic plates move? | A few cm per year. |
What causes tectonic movement? | Radioactive decay causes convection currents. |
What problems do plate movements cause? | Earthquakes and volcanoes. |
What is the % of nitrogen in the atmosphere? | about 80% |
What is the % of oxygen in the atmosphere? | 20% |
Name 2 other gases in the atmosphere. | Carbon dioxide, water vapour, noble gases |
What caused the gases in the early atmosphere? | Volcanoes |
How were the oceans formed? | water vapour condensed |
What gases were present in the early atmosphere? | Carbon dioxide, methane, ammonia, water vapour |
What is the main theory as to how life was formed? | interaction between hydrocarbons, ammonia and lightning. |
What produced the oxygen in the atmosphere? | Plants and algae |
Where does carbon dioxide get removed from the atmosphere? | In sedimentary rocks as carbonates and fossil fuels. |
What is the problem of carbon dioxide being absorbed into the ocean? | Impact on marine environment |
What is causing the increase in carbon dioxide? | Burning fossil fuels. |
How do we separate the gases in the air? | Fractional distillation. |
Why can we separate the gases in the air? | They have different boiling points. |
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