This question is about elements and compounds - AQA - GCSE Chemistry - Question 3 - 2017 - Paper 3
Question 3
This question is about elements and compounds.
3 (a) In 1869 Mendeleev produced an early version of the periodic table.
Figure 4 shows part of Mendeleev's periodic... show full transcript
Worked Solution & Example Answer:This question is about elements and compounds - AQA - GCSE Chemistry - Question 3 - 2017 - Paper 3
Step 1
Why did Mendeleev leave gaps in his periodic table?
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Answer
Mendeleev left gaps in his periodic table to account for undiscovered elements. This arrangement ensured that elements with similar properties were grouped together, thereby fitting the overall pattern.
Step 2
Give one reason why the elements Ti, V, Cr and Mn should not be where Mendeleev placed them.
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The elements Ti, V, Cr, and Mn should not be where Mendeleev placed them because they have different properties from the elements above them and are classified as transition metals.
Step 3
Why, in terms of electrons, is bromine in Group 7?
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Bromine is in Group 7 because it has 7 electrons in its outer shell, which is the highest energy level. This configuration characterizes elements in Group 7, known for their diatomic nature and reactivity.
Step 4
Explain why, in terms of electrons, bromine is more reactive than iodine.
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Bromine is more reactive than iodine because its outer shell is closer to the nucleus, resulting in a stronger force of attraction to its outer electrons. This allows bromine to gain electrons more easily than iodine, which has more electron shells and therefore less attraction to the outer shell.
Step 5
Write the result for sodium iodide solution in Table 1.
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For sodium iodide solution, the result of adding silver nitrate is a yellow precipitate.
Step 6
Write the result for iron(II) chloride solution in Table 2.
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For iron(II) chloride solution, the result of adding sodium hydroxide solution is a green precipitate.
Step 7
Why would a flame test not show the presence of both sodium ions and potassium ions in the mixture?
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A flame test would not show the presence of both sodium ions and potassium ions in the mixture because the flame colors would obscure one another, making it difficult to distinguish between the two.
Step 8
Complete Figure 7 to show the displayed structure of ethanoic acid.
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The displayed structure of ethanoic acid is:
H
|
H–C–C
|
O–H
Where the hydroxyl (-OH) functional group is included.
Step 9
Explain why ethanoic acid has a higher pH value than hydrochloric acid of the same concentration.
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Ethanoic acid has a higher pH value than hydrochloric acid of the same concentration because it is a weak acid and does not fully ionize or dissociate in solution. This results in a lower concentration of hydrogen ions compared to hydrochloric acid, which is a strong acid.
