A chemist is given samples of three unknown elements, X, T and J. These letters are not the chemical symbols of the elements.
Element X is a soft, silvery metal. It reacts with water to form hydrogen and a solution of a compound with the formula XOH.
Explain what the formula XOH tells you about the group that X is in.
The chemist adds 0.78 g of X to excess water and collects 240 cm3\mathrm{cm^{3}}cm3 of hydrogen at room temperature and pressure.
2X(s)+2H2O(l)→2XOH(aq)+H2(g)2\mathrm{X(s)} + 2\mathrm{H_{2}O(l)} \rightarrow 2\mathrm{XOH(aq)} + \mathrm{H_{2}(g)}2X(s)+2H2O(l)→2XOH(aq)+H2(g)
Determine the relative atomic mass of X and identify element X. The volume of one mole of any gas at room temperature and pressure is 24 000 cm3\mathrm{cm^{3}}cm3.
Element T is a colourless gas. Its atoms have 8 electrons in their outer shell and it does not form any compounds. State the group that T is in and give one use of T that depends on its lack of reactivity.
Element J is a red-brown liquid at room temperature. It reacts with element X to form a white solid with the formula XJ. Deduce the group that J is in and identify element J.
41 exam-style questions on Edexcel GCSE Chemistry 7.1 Group 1, covering 7.1.1 Classifying elements by group in the periodic table and 7.1.2 Properties and reactions of the alkali metals. Each one has a worked solution and a mark scheme showing where the marks go.