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83 Cards in this Set
- Front
- Back
Why is the periodic table called the periodic table?
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Similar properties of elements occur at regular intervals
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Who attempted to classify the elements by arranging them in order of their atomic weights?
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Newlands, and then Mendeleev
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The columns in which elements with similar properties are organised is called
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Groups
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Why was Newland's periodic table not accepted by other scientists?
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It was incomplete and since the elements were ordered in atomic weight this made some elements being placed inappropriately
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How did Mendeleev overcome the problems faced by Newland?
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He left gaps for the elements that he thought had not been discovered yet
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The modern periodic table is arranged by
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Atomic (proton) number
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Elements in the same group have the same
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Number of electrons in their outer shell
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Properties of Group 1 elements: (5)
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All alkali metals
Low density React with non metals to form ionic compounds with a charge of +1; these compounds are white solids which dissolve in water to form colourless solutions React with water, releasing hydrogen Form hydroxides which dissolve in water to form alkaline solutions |
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In Group 1, the further down the group an element is: (2)
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The more reactive the element - because electrons are more easily lost as the number of shells increases
The lower its melting and boiling point |
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Compared with elements in Group 1, transition metals: (3)
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Have higher melting and boiling points (except mercury)
Are stronger and harder Are much less reactive as they do not react as vigorously with water or oxygen |
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Properties of transition metal ions: (3)
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Can form different charges
Form different coloured compounds Useful catalysts |
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The elements in Group 7 of the periodic table are known as
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Halogens
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Halogens react with metals to form an ionic compound in which the halide ion carries a charge of
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-1
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In Group 7, the further down the group an element is: (2)
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The less reactive the element - because electrons are less easily gained
The higher the melting and boiling point |
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What type of water readily forms lather with soap?
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Soft water
Hard water reacts with soap to form scum and so more is needed |
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What does not form scum with hard water?
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Soapless detergents
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What does hard water contain? Why?
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Magnesium and calcium ions which comes from being in contact with rocks
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What is the difference between permanent and temporary hard water?
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Permanent hard water remains hard when boiled whereas temporary hard water becomes soft once boiled
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What does temporary hard water contain?
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Hydrogencarbonate ions (HCO3-)
These decompose on heating to form carbonate ions which react with the calcium and magnesium ions to form precipitates |
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What are the disadvantages of hard water? (2)
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Can increase costs as more soap is needed
Produces scale when heated which reduces the efficiency of kettles |
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What are the advantages of hard water? (2)
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The calcium compounds in it are good for the development of bones and teeth
Can also reduces heart disease |
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How can hard water be softened? (2)
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By removing the calcium and magnesium ions which can be done by:
Adding sodium carbonate which forms a precipitate of calcium carbonate and magnesium carbonate Using a water softener which uses ion exchange columns containing sodium or hydrogen to replace the magnesium and calcium |
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Why may chlorine be added to drinking water?
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Reduce the number of microbes
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Why may fluorine be added to drinking water?
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To help dental health
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What is done to tap water to help improve the taste and quality?
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Pass them through filters which contain carbon, silver and iron exchange resins
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How can pure water be made and what are the disadvantages of it?
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Distillation - evaporating and then condensing
Lots of energy is needed to evaporate the water and so pure water is expensive to make and buy |
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What does calorimetry measure?
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The amount of energy released when a substance is burnt
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How can calorimetry be done?
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Burning the fuel underneath water in a glass or metal container
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The amount of heat energy released =
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the mass of water heated x 4.2 x change in temperature of the water
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The amount of heart energy released (Q) is measured in
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Joules (J)
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The mass of water heated (m) is measured in
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Grams (g)
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c in the equation Q=mcT refers to
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the energy required to raise the temperature of 1g of water by 1C (4.2)
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The change in temperature of the water (T) is measured in?
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Celsius (C)
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What reactions would the calorimetry method be used for? (2)
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Solids with water
Neutralisation reactions |
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Breaking bonds and forming bonds requires
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Energy
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In an exothermic reaction
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The energy released from forming new bonds if greater than the energy needed to break existing bonds
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In an endothermic reaction
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The energy released from forming new bonds is less than the energy needed to break the existing bonds
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Catalysts
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Provide a different pathway for chemical reactions which need a lower activation energy
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Why is hydrogen burned (in air)?
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To use as a fuel in combustion engines or fuels cells which produce electricity
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What flame colour is a result of lithium compounds?
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Crimson
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What flame colour is a result of sodium compounds?
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Yellow
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What flame colour is a result of potassium compounds?
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Lilac
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What flame colour is a result of calcium compounds?
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Red
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What flame colour is a result of barium compounds?
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Green
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Aluminum, calcium and magnesium ions + hydroxide solution ->
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White precipitates
(Only aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution) |
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Copper 2 + sodium hydroxide solution ->
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Blue precipitate
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Iron 2 + sodium hydroxide solution ->
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Green precipitate
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Iron 3 + sodium hydroxide solution ->
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Brown precipitate
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Carbonate + dilute acid ->
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Carbon dioxide + salt + water
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How can we test for carbon dioxide
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Turns limewater cloudy
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Chloride ions + silver nitrate solution ->
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Silver chloride - which is a white precipitate
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Bromide ions + silver nitrate solution ->
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Silver bromide - which is a cream precipitate
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Iodide ions + silver nitrate solution ->
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Silver iodide - which is a yellow prepitate
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Sulfate ions + barium chloride solution + dilute hydrochloric acid ->
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White precipitate
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Concentration of solution =
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Number of moles of solute/ volume of solution
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What is the concentration of a solution measured in?
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Moles/dm^3
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What is the volume of solution measured in?
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Dm^3
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Titration
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Finds out how much of an acid and alkali is needed to neutralise each other (using an indicator)
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What raw materials are used in the Haber process?
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Nitrogen and hydrogen
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How is the nitrogen and hydrogen used in the Haber process obtained?
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Nitrogen is taken from the air
Hydrogen is from natural gas |
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How is ammonia made?
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Purified nitrogen and hydrogen are passed over a catalyst of iron at 450C (high temperature) and 200 atmospheres (high pressure). The gases react to form ammonia. As it cools the ammonia liquefies and is then removed, the remaining hydrogen and nitrogen are recycled
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Nitrogen + hydrogen -><-
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Ammonia
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Equilibrium
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Reactions occur at the exactly same rate in each direction
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If the temperature is raised in an endothermic reaction the yield
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Increases
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If the temperature is decreased in an endothermic reaction the yield
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Decreases
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If the temperature is raised in an exothermic reaction the yield
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Decreases
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If the temperature is decreased in an exothermic reaction the yield
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Increases
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Why will a raise in temperature favour the endothermic reaction?
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Endothermic reactions require heat energy
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In gaseous reactions, an increase in pressure will favour the reaction that produces
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The least number of molecules
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What is the functional group and general formula of alcohols?
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-OH
CnH2n+1OH |
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What is the functional group of carboxylic acids?
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-COOH
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What us the functional group of esters?
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-COO-
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Alcohols, carboxylic acids and esters are all
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Organic compounds containing carbon hydrogen and oxygen
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What are the first three members of the alcohols?
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Methanol
Ethanol Propanol |
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Properties of methanol, ethanol and propanol (3)
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Dissolves in water to form a neutral solution
Reacts with sodium to produce hydrogen Burns in air |
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Uses of alcohols
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Solvents, fuel and alcoholic drinks
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Ethanoic acid is the main acid in
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Vinegar
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Alcohol + oxygen ->
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Carbon dioxide + water
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Alcohol + oxidising agent ->
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Carboxylic acid + water
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Properties of carboxylic acids
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Dissolve in water to produce acidic solutions
React with carbonates to produce carbon dioxide Do not ionise completely when dissolved in water and so are weak acids |
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Carboxylic acid + alcohol -><-
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Ester + water
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Ethanol + ethanoic acid ->
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Ethyl ethanoate
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Uses of esters
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Perfumes and food flavourings because of their smells
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