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The Group 7 elements are known as the halogens - OCR Gateway - GCSE Chemistry - Question 17 - 2019 - Paper 4
Question 17
The Group 7 elements are known as the halogens. The halogens have similar chemical properties. Their physical properties vary with increasing atomic number. (a) L... show full transcript
Worked Solution & Example Answer:The Group 7 elements are known as the halogens - OCR Gateway - GCSE Chemistry - Question 17 - 2019 - Paper 4
Step 1
i) Predict the molecular formula and atomic radius of astatine.
Answer
The molecular formula for astatine can be predicted as At₂, following the trend seen in the other halogens. The atomic radius of astatine is expected to be larger than iodine's, therefore, a reasonable estimate for the atomic radius of astatine is around 160 pm.
Step 2
Step 3
iii) Explain your answer to (ii) in terms of the reactivity of the halogens.
Answer
The reactivity of halogens decreases down the group, meaning that bromine, being higher in the reactivity series than iodine, can displace iodine from sodium iodide solution. This displacement reaction occurs because bromine can oxidize iodide ions (I⁻) to iodine (I₂), demonstrating that bromine is more reactive than iodine.