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The first ionisation energy of chlorine is greater than that of sulfur - CIE - A-Level Chemistry - Question 32 - 2019 - Paper 1
Question 32
The first ionisation energy of chlorine is greater than that of sulfur. Which factors contribute to this? 1. Chlorine has more protons in its nucleus than sulfur do... show full transcript
Worked Solution & Example Answer:The first ionisation energy of chlorine is greater than that of sulfur - CIE - A-Level Chemistry - Question 32 - 2019 - Paper 1
Step 1
1. Chlorine has more protons in its nucleus than sulfur does.
Answer
Chlorine has 17 protons compared to sulfur's 16. This higher nuclear charge in chlorine increases the attraction between the nucleus and the electrons, requiring more energy to remove an electron, thus contributing to a higher ionisation energy.
Step 2
2. Chlorine has greater electron shielding than sulfur does.
Answer
While chlorine has more protons, it does not have greater electron shielding than sulfur as it has fewer inner electron shells. In fact, the electron shielding is less effective in chlorine because there are fewer pairs of electrons that can repel the valence electrons, resulting in a greater effective nuclear charge felt by the outer electrons.
Step 3
3. The covalent bonds in chlorine molecules are stronger than those in sulfur molecules.
Answer
The strength of covalent bonds in molecules does not directly affect ionisation energy but does indicate that chlorine molecules are more stable and require more energy to break apart. However, this factor is not a direct contributor to the first ionisation energy of chlorine compared to sulfur.