May/June 2026 Paper 22

Oxygen reacts with many elements. State the total number of electrons that occupy the 2p sub-shell in an oxygen atom.

Name the orbital that contains the highest energy electron in an oxygen atom, and draw the shape of this orbital.

Lithium reacts with oxygen to produce lithium oxide, Li${}_2$O. Li${}_2$O is a white solid with a melting point over $1400{}^{\circ }\mathrm{C}$. Draw a dot-and-cross diagram to show the arrangement of all the electrons in Li${}_2$O.

Li${}_2$O reacts with water to produce a solution with pH greater than 10. State the name of a Period 3 oxide that behaves in the same way as Li${}_2$O when added to water.

Construct an equation for the reaction of Li${}_2$O with water.

Identify all the Period 3 chlorides that are solid at room temperature and that react with water to produce an acidic solution.

LiNO${}_3$ decomposes on heating to produce Li${}_2$O, O${}_2$ and a brown gas. Identify the brown gas.

Ammonia is made in the Haber process.

A temperature of $400\text{–}450{}^{\circ }\mathrm{C}$ is used in the Haber process. State two other conditions used in the Haber process.

Describe how the initial rate of the forward reaction changes, if at all, when a temperature greater than $450{}^{\circ }\mathrm{C}$ is used. Explain your answer. Assume all other variables remain constant.