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| Frage | Antworten |
| How many elements are there? | about 100 |
| describe the relative charges of protons neutrons and electrons | |
| Why do atoms have no overall chage | Because the numbers of electrons and protons are the same in a neutral atom |
| What is the relative masses of the proton , neutron and electron | proton = 1 neutron = 1 electron - 1/2000 or v small |
| How do you calculate the number of neutrons in an atom | take the atomic number from the mass number |
| why are the noble gasses unreactive | They are unreactive because their atoms have stable arrangements of electrons. |
| what is conservation of mass theory | No atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants. example - if you decompose 20 g of calcium carbonate you produce 11.2 g of calcium oxide and 8.8 g of carbon dioxide |
| What is limestone? | Limestone, mainly composed of the compound calcium carbonate (CaCO3), is quarried and can be used as a building material. |
| Describe the thermal decomposition of limestone | Calcium carbonate can be decomposed by heating (thermal decomposition) to make calcium oxide and carbon dioxide. |
| Which other carbonates can be decomposed. ? can they all be decomposed in the lab ? | The carbonates of magnesium, copper, zinc, calcium and sodium decompose on heating in a similar way.not all carbonates of metals in Group 1 of the periodic table decompose at the temperatures reached by a Bunsen burner. |
| Describe the reaction between calcium oxide and water | Calcium oxide reacts with water to produce calcium hydroxide, which is an alkali that can be used in the neutralisation of acids. |
| describe how lime water is used to test for carbon dioxide? | A solution of calcium hydroxide in water (limewater) reacts with carbon dioxide to produce calcium carbonate. Limewater is used as a test for carbon dioxide. Carbon dioxide turns limewater cloudy. |
| describe the reaction between carbonates and acid | Carbonates react with acids to produce carbon dioxide, a salt and water. Limestone is damaged by acid rain. |
| describe how cement , mortar and concrete are made | Limestone is heated with clay to make cement. Cement is mixed with sand to make mortar and with sand and aggregate to make concrete. |
| what is the formula of calcium hydroxide? | Ca(OH)2 |
| What is an ore ? | Ores contain enough metal to make it economic to extract the metal. The economics of extraction may change over time. |
| How are most metals found? | 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. |
| How are metals less reactive than C extracted ? | 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. |
| What is reduction ? | the removal of oxygen |
| How are metals more reactive that C extracted and why are these metals more expensive? | Metals that are more reactive than carbon, such as aluminium, are extracted by electrolysis of molten compounds. The use of large amounts of energy in the extraction of these metals makes them expensive. |
| How is copper extracted ? | Copper can be extracted from copper-rich ores by heating the ores in a furnace (smelting). The copper can be purified by electrolysis. The supply of copper-rich ores is limited. |
| What is phytomining? | Phytomining uses plants to absorb metal compounds and that the plants are burned to produce ash that contains the metal compounds |
| What is bioleaching? | bioleaching uses bacteria to produce leachate solutions that contain metal compounds. |
| How is copper extracted from copper salts? | Copper can be obtained from solutions of copper salts by electrolysis or by displacement using scrap iron. |
| Why is the extraction of aluminium and titanium expensive? | Aluminium and titanium cannot be extracted from their oxides by reduction with carbon. Current methods of extraction are expensive because: ■ there are many stages in the processes ■ large amounts of energy are needed. |
| Why should we recycle metals? | We should recycle metals because extracting them uses limited resources and is expensive in terms of energy and effects on the environment. |
| List the advantages and disadvantages of limestone products | |
| describe the advantages of using limestone? | |
| describe the disadvantages of using limestone? | |
| what is an element | just 1 type of atom |
| what is a molecule | 2 or more atoms chemically joined - can be an element or compound !! |
| what is a compound | 2 or more different elements chemically joined |
| what sort bonds are formed between non - metals | covalent |
| how are covalent bonds formed | sharing of electrons to give atoms a full outer shell and stable arrangement |
| what sort of bonds form between metals and non - metals | ionic |
| how do ionic bonds form | metal atoms lose one or more electrons to form positively charged ions. non-metal atoms gain electrons to form negatively charged ions. the oppositely charged ions attract each other strongly (electro static forces) |
| limewater goes cloudy when mixed with carbon dioxide. explain why using an equation | calcium carbonate is formed and is insoluble calcium hydroxide + carbon dioxide = calcium carbonate + water |
| explain why acids damage limestone | acids react with calcium carbonate producing carbon dioxide , salt and water. the salt dissolved in water and so the amount of limestone decreases |
| farmers spread calcium hydroxide on fields with acidic soils. explain why | calcium hydroxide reacts with acids because calcium hydroxide is an alkali and the reaction is neutralisation, it increases the pH of the soil which is better for certain plants |
| what are the advantages and disadvantages for an area in which limestone is quarried | advantages- 1.more employment 2.more customers and trade for local business 3. improved roads disadvantages 1. dust and noise 2.more traffic 3. loss of wildlife habitat |
| how does limestone remove sulphur dioxide from power stations | it reacts with sulphur dioxide to form calcium sulfate (neutralisation) |
| what does calcium carbonate + acid produce | salt + water + carbon dioxide |
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