2476332
| Pregunta | Respuesta |
| How did Newland and Mendeleev arrange the elements? | By atomic mass |
| What do the groups contain? | Elements with similar properties. |
| Why was the atomic mass order incorrect? | Some elements were in inappropriate groups for their properties. |
| What did Mendeleev do that was innovative? | Left gaps for undiscovered elements. |
| How have elements been ordered since the early 20th century? | By the atomic number (proton number) |
| What is important about elements found in the same group? | They have the same number of electrons in their outer shell. |
| What are elements in group 1 called? | Alkali Metals |
| What is the charge of group 1 metal ions? | +1 |
| What type of compounds are formed from group 1 elements reacting with non-metals? | Ionic compounds |
| What colour are group 1 salts? | White |
| What colour are group 1 salt solutions? | Colourless |
| What are the products when group 1 elements are reacted with water? | Metal hydroxide + hydrogen |
| How does reactivity change down group 1? And why does it change like this? | Increases, because the outer electron is more easily lost. |
| How does the melting point change down group 1 elements? | Gets lower. |
| Give three differences between transition metals and group 1 elements. | Transition metals have a higher boiling point (except from mercury). Transition metals are stronger and harder. Transition metals are less reactive. |
| What colour are transition metal salts? | Various colours |
| Give a use for transition metals. | Catalysts |
| What are group 7 elements called? | Halogens |
| What charge is on halide ions? | -1 |
| How does reactivity change down group 7? And why does it change like this? | It decreases, because it becomes harder to gain an electron to complete a full outer shell. |
| How does the melting point change down group 7? | it increases. |
| What is formed when soft water reacts with soap? | Lather |
| What is formed when hard water reacts with soap? | Scum |
| Which ions cause hard water? | Ca 2+ and Mg 2+ |
| How do these ions get into the water? | The compounds are dissolved when water comes into contact with rocks. |
| What are the 2 types of hard water? | Temporary and permanent. |
| How can we get rid of temporary hardness? | Boil the water |
| What ions are in temporary hard water? | Hydrogen carbonate (HCO3) |
| What ions are formed when hydrocarbonate ions decompose? | Carbonate ions. |
| What are formed when calcium and magnesium react with carbonate ions? | Precipitates |
| why does hard water increase cost? | More soap is needed |
| What is formed when temporary hard water is boiled? | Limescale |
| How does limescale affect appliances? | Reduces their efficiency. |
| Give 2 benefits of hard water. | Good for teeth and bones. And Reduces heart disease |
| Give two ways hard water can be softened. | Add sodium carbonate to precipitate the ions. OR An ion exchange column. |
| What do water filters contain? | Carbon, silver and ion exchange resins. |
| What is added to water to improve dental health? | Fluoride ions |
| Why is chlorine added to water? | To kill microbes. |
| How else can water be purified? | Distillation |
| How can we measure the amount of energy released by a reaction? | Calorimetry ( heating in a glass or metal container). |
| What is the equation used to calculate tje amount of energy? | q=mc∆t q=energy transferr m=mass,g, c=specific heat capacity, j/g ∆t= change in temperature |
| In what unit is energy measured in? | Joules |
| For what reactions can this be used for? | Reactions with solids and and neutralisation reactions. |
| Which type of reaction has reactants of higher energy than its products? | Exothermic. |
| What type of reaction has products at a higher energy than the reactants? | Endothermic |
| What process in a reaction needs energy to be supplied? | Bond breaking |
| During which process in a reaction is energy released? | Bond forming |
| What makes a reaction exothermic? | Energy released from forming bonds is greater than the energy needed to break the bonds. |
| What makes a reaction endothermic? | Energy needed to break the bonds is greater than the energy released from forming bonds. |
| How do catalysts work? | They provide a different pathway with a lower activation energy. |
| What is produced when hydrogen burns in air? | Water |
| For what can this reaction be used for? | combustion engines and fuel cells to produce electricity for vehicles. |
| what is the flame colour for potassium? | Lilac |
| What is the flame colour for calcium? | Red |
| Which ions give White precipitates with sodium hydroxide? | Aluminium, calcium and magnesium |
| Which ion's precipitate re-dissolves in excess sodium hydroxide? | Aluminium |
| What colour precipitate is the Fe(II) precipitate? | Green |
| What is formed when carbonates react with an acid ? | Salt, carbon dioxide and water |
| What is the test for carbon dioxide? | Bubble through limestone, which turns cloudy. |
| What is used to test for halides? | Silver nitrate solution with nitric acid. |
| What is the colour for chloride? | White |
| What is the colour for bromide? | Cream |
| What is the colour for Iodide? | Yellow |
| What is used to test for sulphate ions? | Barium chloride with dilute hydrochloric acid. |
| How do we measure the amount of acid and alkali in a reaction? | using titration and a suitable indicator. |
| For what do we use titration results? | To calculate the concentration of one reactant from the knowledge of the other concentration. |
| What are the raw materials for the Haber process? | Nitrogen and hydrogen |
| Where does nitrogen come from? | The air(fractional distillation) |
| Where does the hydrogen come from? | Methane (natural gas) or other sources |
| What catalyst is used? | Iron |
| What temperature is used | About 450 degrees Celsius (high) |
| What pressure is used? | 200 atmospheres (high) |
| What is the main problem with the reaction? | it is reversible |
| What happens to the ammonia? | Liquified and removed |
| What happens to the nitrogen and hydrogen? | Recycled |
| When is equilibrium reached? | When the reactions occur at the exact same rate. |
| What happens to the yield of ammonia at high temperatures? | Decreases as the endothermic reaction takes place more due to taking in the heat. |
| What happens to the yield of ammonia at high pressures? | Increases as the reaction favours the direction producing the least molecules. |
| What else needs to be considered when looking for optimum conditions for industrial reactions? | The rate of reactions. |
| What is the functional groups of alcohols? | -OH groups |
| What are the first three alcohols? | Methanol, ethanol, propanol |
| Give three properties of alcohols. | Dissolve in water to produce a neutral solution. React with sodium to produce hydrogen. Burn in air. |
| Give two uses of alcohols. | Fuels and solvents |
| Which alcohol is found in alcoholic drinks? | Ethanol |
| What reaction changes ethanol into ethanoic acid? | Oxidation |
| What is ethanoic acid? | Vinegar |
| What is the functional group of carboxylic acids? | -COOH |
| Give three properties of carboxylic acids. | Dissolve in water to give acidic solutions. React with carbonates to produce carbon dioxide. React with alcohols to produce esters. |
| What is used as a catalyst in an esterification reaction? | Acid |
| Why are carboxylic acid weak acids? | They do not ionise completely when dissolved in water. |
| Do weak acids have a higher or lower pH value? | Higher |
| Which ester is produced from ethanol and etahnoic acid? | Ethyl ethanoate |
| What is the functional group of esters? | -COO- |
| Give 2 properties of esters. | Volatile and distinctive smell |
| For what are esters used? | Flavourings and perfumes. |
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