GCSE chemistry 3

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GCSE chemistry 3
2013-04-08 05:17:08


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  1. You are going to find out what happens when you mix a solution of a halogen to a solution of a compound with another halogen . Predict the results using the table and filling in the empty table 

  2. What do your results prove about the reactivity of the halogens - use the word displace or displacement in your answer
    More reactive halogens will displace less reactive halogens and the reactivity decreases as we go down the group
  3. Write the word and chemical equations for the reactions which occurred
    • Chlorine + potassium -> potassium + bromide  
    •                 bromide         Chloride 
    • Cl2 + 2KBr ---> 2KCl + Br2 
    • Cl2 + 2Br- ----> 2Cl- + Br2 

    • Cl2 + 2KI -----> 2KCl + I2 
    • Cl2 + 2I- ------> 2Cl- + I2 

    • Br2 + 2KI -----> 2KBr + I2 
    • Br2 + 2I- ------> 2Br- + I2
  4. Trends in group 7
    Melting and boiling points increase as you go down the group . Reactivity decreases as you go down the group
  5. The elements in group 0 are called the
    Noble gases
  6. The elements in group 0 are
    • Helium 
    • neon 
    • argon 
    • krypton 
    • xenon
    • radon
  7. All the noble gases are
    • Non metals and have very low melting and boiling points , hence they are all gases at room temperature . They are all chemically unreactive
    • and so do not form compounds with any other elements and exist simply as individual atoms I.e He , Ne , Ar , Kr , Xe and Rn (rather than as molecules where 2 atoms join as with all other gases eg H2 , O2 , Cl2) . They are unreactive and monatomic because their outer electron shell is already full so the atoms have no tendency to gain , loose or share electrons
  8. uses of noble gases
    They are used as inert (unreactive) gases in filament lamps and electrical discharge tubes
  9. In the periodic table between groups 2 and 3 is a block of elements known as the
    Transition elements . These are all metals
  10. The transition elements have similar a properties and some special properties because
    A lower energy level (inner shell) is Being filled in the atoms of the elements between groups 2 and 3 , this is because the third energy level Can hold up to 18 electrons , once two electrons have occupied the fourth energy level
  11. Compared with group 1 , transition elements
    • Have higher melting point (except mercury) and higher densities
    • are stronger 
    • are much less reactive and So don't react as vigorously with water or oxygen
  12. Many transition elements have ions with
    Different charges , for example iron atoms can react to give away 2 electrons to form Fe2+ ions or give away 3 electrons Fe3+ ions . We use Roman numerals to show which charge the iron ions have in a compound e.g. There are two forms of iron oxide iron 11 oxide (formula FeO) and iron 111 oxide (formula Fe2O3)
  13. Nb if you aren't told in the name you can always assume all transition elements except silver Are
    +2 , silver is always +1
  14. Unlike group 1 metals (which form white ionic compounds that dissolve to form colourless solutions) , transition metals form
    coloured ionic compounds that often dissolve in water to form coloured solutions e.g. Copper 11 sulphate dissolves to form a bright blue solution . Iron 11 compounds are usually green coloured and iron 111 compounds are usually brown coloured . (E.g. Iron 111 oxide is brown)
  15. Transition metals are useful as
    • Catalysts (substances that speed up a reaction without being used up themselves) 
    • Examples from the previous topic include iron in the haber process to make ammonia , nickel in the hydrogenation of vegetable oils to make margerine
  16. The vertical columns are called
    Groups . They are numbered 1 to 0
  17. The horizontal rows are called
    Periods there are 7 of these
  18. elements of the same group have the same sort of properties . What are the names of group 1 , group 7 and group 8
    alkali metals , halogens , noble gases
  19. As you go down a group the number of electrons
    Increases . Therefor the size of the atoms increases . But in any one group the number of electrons in the outer shell is always the same
  20. In group 1 there is .. Electron(s) in the outer shell
  21. In group 7 there are .. Electron(s) in the outer shell
  22. In group 8 there are .. Electron(s) in the outer shell
  23. If you didn't have a periodic table explain 3 ways in which you could decide if it was a metal or a nonmetal
    • Metals would conduct electricity unlike nonmetals 
    • metals would conduct heat unlike nonmetals
    • Metals would be sonorous unlike nonmetals
  24. Describe an experiment you could do to prove whether an element was a metal or nonmetal
    Use the element in a circuit and see if the bulb lights up , if it does it means the element conducts electricity and therefor is a metal . However there is an exception because graphite is a nonmetal but still conducts electricity
  25. Why is the radius of a Cl- radius larger tthe the radius of a Cl atom
    A Cl- ion has more electrons , electrons repel each other , so a larger radius
  26. What is the trend In melting and boiling points as you go down group 7
    they increase
  27. The halogens exist as diatomic molecules . What does this mean
    • 2 atoms in the molecule 
    • noble gases are monatomic they exist their own
  28. Why do halides form ions
    They need to gain an electron so they have a Full outer energy level
  29. what type of bonding does chlorine form with nonmetals
  30. What is a test for chlorine
    See if it bleaches damp litmus if it does Cl is present
  31. Basic why does the reactivity decrease as you descend group 7
    • Larger atoms 
    • outer electrons are more shielded 
    • so attraction from nucleus is less so electrons are gained less easily
  32. What happens to the atomic mass of the elements as we descend group 1
  33. Why
    Because as we descend down the group the number of protons and neutrons increases
  34. As we descend down group 1 what happens to the size of the atoms and ions
  35. Why
    More full energy levels
  36. Why is the radius of a sodium ions less than the radius of a sodium atom
    The sodium ion has 1 less electron
  37. What have all the alkali metals have in common
    They all have 1 electron in their outer energy level
  38. Why does this make them all reactive metals
    Its easy to remove 1 electron
  39. On descending group 1 what happens to the melting and boiling points of the elements
    They decrease
  40. The horizontal rows of the periodic table are know as periods . As we move across the period of a table
    Each successive element has one more electron in its outer energy level than the element before it . This carries on until the elements at the far right of the table have completely full outer energy levels , so these elements are very stable and unreactive
  41. While all of the alkali metals react in similar ways As a result of the single electron in their outer energy level , there's some definite trends in reactivity which can be only explained by looking in more detail at the structure of the atoms
    Reactivity increases when we descend the group because the atoms get bigger , so the electron is held less tightly by attraction to the positive nucleus because it is screened by other other full energy levels of electrons . This means the outer electron is lost more easily , so the element is more reactive
  42. As we go down group 1 why does the density increase
    Because the atoms get bigger
  43. Why do melting points and boiling decrease as we go down group 1
    Because the metallic bonds between the Electrons  and the positive nuclei get less as the atoms hey larger
  44. The patterns of behaviour of the elements in group 7 can be explained by the arrangement of electrons in their highest occupied energy level . The trend for the halogens is the opposite to that for the alkali metals .
    Going down the group the elements become less reactive because electrons are gained , for ionic or covalent bonding , less and less easily . This is because the larger the atom becomes , the more full energy levels of electrons there are screening the outer electrons from the attractive positive force of the nucleus . This means that the tendency to attract electrons gets less and less