Predicting the properties of francium
4 marks · NormalAnswer the following questions about francium and its properties.
Explain why we can predict the properties of francium, even though it is extremely rare.
State one property francium would have as a solid and one as an aqueous compound.
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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(a) Because francium is in Group 1, we can use trends and patterns in the properties of alkali metals to predict how it would behave. · must show Periodic trends, Group 1 behaviour
(b) Solid: very soft; Aqueous compound: forms a strongly alkaline solution. · must show Solid property: soft, melts around room temperature, silvery, Aqueous property: strongly alkaline solution, colourless
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Marking points
E1 (a) · 1 mark · Mentions that elements in the same group show similar trends/properties are periodic.
E2 (a) · 1 mark · States that predictions are made by using trends or properties of other Group 1 elements.
B1 (b) · 1 mark · States a solid property, e.g., very soft/low melting point/silvery.
B2 (b) · 1 mark · States an aqueous property, e.g., forms a strongly alkaline solution/compound is colourless and soluble.
Worked solution
a) The properties of elements in the same group show trends, letting us predict francium's properties from other alkali metals. So, even though francium is rare, we can make accurate predictions.
b) As a solid, francium would be very soft. In aqueous solution, francium hydroxide would form a strongly alkaline, colourless solution.