Explaining the trend in the reactivity of the halogens
2 marks · HardAstatine is the halogen below iodine in Group 7. Predict the colour and state you would expect for astatine at room temperature, based on group trends.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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Must show: Prediction: astatine is a very dark grey or black solid at room temperature
Also accept: Solid, very dark grey or black; Solid, black, very dark colour
Common mistakes: Saying astatine is a gas; Saying astatine is coloured like chlorine or bromine
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Marking points
B1 · 1 mark · Correctly predicts astatine is a solid at room temperature.
B2 · 1 mark · Correctly predicts astatine is a very dark grey or black in colour.
Worked solution
Down Group 7, the halogens change from gases (fluorine, chlorine), to liquid (bromine), to solids (iodine) at room temperature. Iodine is a purple-black solid, so the next element, astatine, is predicted to be a darker solid.
Therefore, astatine would be a very dark grey or black solid at room temperature.