Group I Properties (Cambridge (CIE) O Level Chemistry): Exam Questions

Choose an element from the list below which best fits the description.

An element which reacts with cold water.

It is a solid at room temperature and exists as diatomic molecules, X₂.

It can form two oxides, XO and X₂O₃.

This element has a hydride of the type XH₃.

It has a macromolecular structure similar to that of carbon.

For each of the following, give the name of an element from Period 3 (sodium to argon), which matches the description.

An element which is gaseous at room temperature and pressure

An element that is added to water to kill bacteria.

An element that forms a basic oxide of the type XO.

An element that forms an amphoteric oxide.

An element that reacts vigorously with cold water to produce hydrogen.

The properties of the first four Group I elements are shown in the table.

Answer these questions using only the information in the table.

Describe the general trend in the boiling points of the Group I elements.

Explain why it is difficult to predict the density of rubidium.

Deduce the state of rubidium at 45 °C. Explain your answer.

For each of the following, select an element from Period 4, potassium to krypton, which matches the description.

A metal that reacts rapidly with cold water to form a compound of the type M(OH)₂ and hydrogen.

Its only oxidation state is 0.

It has a macromolecular oxide, XO₂, which has similar physical properties to those of diamond.

This is one of the metals alloyed with iron in stainless steel.

It can be reduced to an ion of the type X^–.

It can form a covalent hydride having the formula H₂X.

Its soluble salts are blue and its oxide is black.

It is a liquid at room temperature.

Rubidium and strontium are very reactive metals at the top of the reactivity series. Because their ions have different charges, their compounds behave differently when heated.

The formulae of the ions of these two elements are Rb⁺ and Sr²⁺.

Explain why these metals, which are in different groups, form ions which have different charges.

Strontium carbonate is similar to calcium carbonate. It is insoluble in water and it decomposes when heated. Rubidium carbonate is soluble in water and does not decompose when heated.

i) Describe a method to prepare a pure sample of the insoluble salt, strontium carbonate, by precipitation.

[4]

ii) Complete the equation for the decomposition of strontium carbonate.

SrCO₃ → ............ + ............

[1]