This question is about Period 3 elements - AQA - A-Level Chemistry - Question 3 - 2020 - Paper 1
Question 3
This question is about Period 3 elements.
Figure 2 shows the second ionisation energies of some elements in Period 3.
Draw a cross (x) on Figure 2 to show the seco... show full transcript
Worked Solution & Example Answer:This question is about Period 3 elements - AQA - A-Level Chemistry - Question 3 - 2020 - Paper 1
Step 1
Draw a cross (x) on Figure 2 to show the second ionisation energy of silicon.
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Answer
A cross should be drawn at approximately 1960 kJ mol⁻¹ on the graph, which represents the second ionisation energy of silicon.
Step 2
Identify the element in Period 3, from sodium to argon, that has the highest second ionisation energy.
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Answer
Element: Na
Step 3
Give an equation, including state symbols, to show the process that occurs when the second ionisation energy of this element is measured.
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Answer
Equation: Na(g)→Na+(g)+e−
Step 4
Explain why the atomic radius decreases across Period 3, from sodium to chlorine.
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Answer
As we move across Period 3 from sodium to chlorine, the number of protons in the nucleus increases, which raises the nuclear charge. This increased positive charge pulls the electrons closer to the nucleus, resulting in a decrease in atomic radius. Additionally, while shielding remains similar due to electrons being added to the same shell, the effective nuclear charge felt by the outer electrons increases, further contributing to the decrease in atomic radius.
Step 5
Identify the element in Period 3, from sodium to chlorine, that has the highest electronegativity.
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Answer
Element: Chlorine
Step 6
Give an equation for the reaction of phosphorus burning in air to form phosphorus(V) oxide.
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