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) (i) Why did Mendeleev leave gaps in his periodic table?
3 (a) (ii) Give one reason why the elements Ti, V, C... 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 accommodate undiscovered elements. This allowed the table to maintain a pattern where elements with similar properties were organized in the same columns or groups.
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 exhibit very different properties compared to the elements in the groups above them, indicating their position was not consistent with the patterns he established.
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 for this element. This arrangement of electrons defines its chemical behavior 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 it has an outer shell that is closer to the nucleus. This results in a stronger force of attraction to incoming electrons, allowing bromine to gain an electron more easily compared to iodine, which has a larger atomic radius and less effective nuclear charge.
Step 5
Write the result for sodium iodide solution in Table 1.
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The result of adding silver nitrate to sodium iodide solution is a yellow precipitate.
Step 6
Write the result for iron(II) chloride solution in Table 2.
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The result of adding sodium hydroxide solution to iron(II) chloride 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 because one color obscures the other. Since both ions produce distinct colors, only the color of one of them would be visible.
Step 8
Complete Figure 7 to show the displayed structure of ethanoic acid.
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The displayed structure of ethanoic acid includes two carbon atoms, one of which is bonded to an -OH group, indicating the presence of a carboxylic acid.
Step 9
Explain why ethanoic acid has a higher pH value than hydrochloric acid of the same concentration.
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Ethanoic acid is a weak acid, meaning it is not fully ionized in solution, allowing it to produce fewer hydrogen ions compared to hydrochloric acid, which is a strong acid that completely ionizes. This results in a higher pH for the ethanoic acid solution.
