Chemisrty Unit 3

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  • Created by: Emily
  • Created on: 15-05-13 10:40
Why was Newlands' work critisised?
The pattern broke down on the third row / he mixed up metals and non-metals / didn't leave gaps for undescovered elements / some boxes had more than one element in them
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What did Mendeleev do differently to Newlands?
Put elements in order of atomic mass / left gaps for undiscovered elements / kept elements with similar properties in the same groups
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What did Mendeleev's periodic table help him to do?
Predict the properties of new elements which were yet to be discovered
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How are elements on the modern periodic table arranged?
By their eletronic structure
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What is an elements group number equal to?
The number of electrons in its outermost shell
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If an electron is furthur away from the nucleus, is there more or less attraction?
Less
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What is the affect of lots of inner electrons know as?
Shielding
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Are electrons lost more easily furthur away or closer to the nucleus?
Further away, because increased distance and increased shielding means its more easily lost due to less attraction
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As you go down Group 1, what's the trend in reactivity?
Reactivity increases
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Give 3 properties of the Group 1 metals
Lower melting and boiling points / low density / one outer shell electron
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What type of bonds form between Group 1 metals and non-metals?
Ionic bonds and the Group 1 metals become 1+ ions
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What is produced by Group 1 metals in ionic compounds?
White compounds that dissolve in water to form a colourless solution
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Describe the reactiion between Group 1 metals and water
A vigourous reaction, the metals float and fizz on the surface of the water. Hydrogen gas is produced and can be tested for by using a lit splint which gives a 'sqeaky pop' if hydrogen is present
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As you go down the Group 7 halogens, explain why they become less reactive
They become less reactive because the outher shell is furthur away from the nucleus, therefore meanung there is less attraction from the nucleus so it is harder to gain an extra electron
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What are some of the properties of Group 7 halogens?
Higher boiling and melting points / exist as molecules / are all non-metals / produce coloured vapours
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What coloured vapours do flourine, chlorine, bromine and iodine produce?
Flourine - yellow gas / chlorine - dense green gas / bromine - red-brown volatie liquid / iodine - dark grey solid OR purple vapour
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When a Group 7 halogen forms an ionic compound - what is the charge on their ions?
1- ions
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A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt - TRUE or FALSE?
True
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Where on the periodic table are the transition metals found?
Between groups 2 and 3
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Describe the main preoperties of transition metals
Good conductors of heat and electricity / dense / strong / shiny metals / high melting and boiling points / less reactive than Group 1 metals
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Transitio metals and their compounds make good...
Catalysts
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What happens to hard and soft water when mixed with soap?
Soft water produces a later and hard water produces a scum (due to calcium ions and magnesium ions in the water reacting with the soap)
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How is scale formed and what effect does it have on appliances?
From heating hard water and it makes appliances less efficient
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How is hard water formed?
From rain falling onto rocks (e.g. limestone or chalk) and dissolving compounds like magnesium sulphate and calcium sulphate to produce magnesium ions and calcium ions in the water
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What are the two types of hardness of water?
Temporary (caused by hydrogencarbon ions) and permanent (caused by dissolved calcium sulphate)
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Give 2 ways of removing permanent hardness from water
1) Adding sodium carbonate to water making the extra carbonate ions react with Ca and Mg ions and form an insouluable precipitate 2) Running water through an ion exchange column containing Na or H ions which are excchanged for Ca and Mg ions
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Name one method of comparing the hardness of water samples
Titration
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Describe the 4 main processes of water treatment (from a reservoir)
1) Water passes through mesh screen to remove big objects 2) Chemicles added to make solids and microbes stick together and fall to bottom 3) Water filtered through gravel to remove all solids 4) Water chlorinated to kill harmful microbes
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How can totally pure water with nothing in it be produced?
By distilation
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What is a reversible reaction?
A reaction where the products of the reaction can react themselves to produce the original reactants
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Explain what is meant by equilibrium
Equlibrium is the position reached whereby the reaction on both sides are both taking place at exactly the ssame rate in both directions
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How can the position of equlibrium be changed? Explain
TEMPERATURE if it's raised the endothermic reaction will increase, if it's reduced the exothermic reaction will increase PRESSURE if it's raised it encourages reaction producing less volume, if it's reduced it encourages the reaction producing more
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Does a catalyst change the equlibrium position?
No, it just speeds up the reaction on both sides
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What does the Haber process do, and what conditions are needed?
Process which produces amonia to make fertiliser, it requires pressure of 200 atmospheres temperature of 450*C and an iron catalyst
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What si the group that all alcohols contain?
-OH
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What is a property that the first 3 alcohols all have in common?
They dissolve completely in water to form neutral solutions
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Give 3 ways in which alcohols can be used
Ethanol is used to produce alcoholic drinks, they can be used as solvents or as fuels
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When alcohols burn in air what is produced?
Carbon dioxide and water
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What type of acids have the functional group -COOH and their names end in -anoic acid?
Carboxylic acids
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What hapens when carboxylic acids react with carbonates?
They produce carbon dioxide and salts ending in -anoate
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What is the difference between a strong acid and a weak acid?
Strong acids are fully ionised wheras weak acids are only partially ionised
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Give the word equation for making ethanoic acid by oxidising ethanol
Ethanol + oxygen ----------> ehtanoic acid + water
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What two kinds of substances react together to form esters?
Alcohols and carboxylic acids
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Give some of the properties of esters
Pleasant smells / volatile / flammable / don't mix well with water / do mix well with alcohols or organic solvants
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How does a solution become more concentrated?
The more solute you dissolve in a given volume, the more crowded the solute molecules are ad the more concerntrated the solution becomes
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What is the concerntration of a solution measured in?
mol/dm3
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What indicator should you use when carrying out titrations and why?
Phenolphthalein or methyl orange because they show an instant colour change and not a gradual one
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When the indicator changes colour during a titration, what does this tell us?
That all the alkali has been nutralised, and therefore the amound of acid needed to nutralised that volume of alkali can be found too
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When finding out the amount of energy released from a chemical reaction, why would you need to insulate the apperatus and use a lid for the apperatus your using?
To reduce the amount of energy lost to the environment and to stop evaporation
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Why is bond forming exothermic?
Because it takes more energy to break the bonds than to make them so the extra energy is released as heat to the surroundings
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Is bond breaking exothermic or endothermic?
Endothermic
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Give an example method of how you can measure the amount of energy fuels produce
Using calorimetry
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What is activation energy?
The minimum amount of needed by reacting particles to break their bonds
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Will a catalyst make the activation energy lower or higher?
Lower
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What is a fuel cell?
An electrical cell that's supplied with fuel and oxygen and uses energy from the reaction between them to generate electricity
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Give 1 advantage and 1 disadvantage to using hydrogen as a fuel
Advatage - when it reacts it only forms water meaning no harmful pollutants. Disadvantage - requires a special expensive engine / hard to store safely / still require energy from another source to make the hydrogen
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Identify a test that can be used to test for metal (positive) ions
The flame test
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If in a flame test your results show a crimson flame, a green flame and a yellow flame what metal ions are present?
Crimson - lithium, green - barium, yellow - sodium
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When using the flame test to identify potassium and calcium, what colour flames would you expect to see?
For potassium a lilac flame and for calcium a red flame
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What is another method for identifying metal ions? Explain it
Using sodium hydroxide solution with the solution of your compound to produce an insoluable solid. Calcium - white, copper - blue, iron(II)- green, iron(III) - brown, aluminium - white (then redisolves in excess NaOH to form colourless solution)
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How can you test for carbonate ions?
Using dilute acid to form carbon dioxide and then useing the limewater test to test for carbon dioxide (acid + carbonate ----------> salt + water + carbon dioxide)
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To test for chloride, bromide or iodide ions, we add them to dilute nitric acid followed by silver nitrate solution. What colour precipitates do they give?
Chloride ions give a white precipitate of silver chloride, bromide ions give a cream precipitate of silver bromide, and iodide ions give a yellow precipitate of silver iodide
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Other cards in this set

Card 2

Front

What did Mendeleev do differently to Newlands?

Back

Put elements in order of atomic mass / left gaps for undiscovered elements / kept elements with similar properties in the same groups

Card 3

Front

What did Mendeleev's periodic table help him to do?

Back

Preview of the front of card 3

Card 4

Front

How are elements on the modern periodic table arranged?

Back

Preview of the front of card 4

Card 5

Front

What is an elements group number equal to?

Back

Preview of the front of card 5
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lionsgate52

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well done. want claps?

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