Group 2 - the alkaline earth metals

how do the group 2 metals form an outer shell

lose two electrons to form 2+ ions

atomic radius down the group

increases down the group due to additional electron shells

Reactivity

increased electron shielding down the group makes the outer electrons easier to lose. Therefore reactivity of the group 2 metals increases down the group

Ionisation energy

the first ionisation energy of group 2 metals decreases down the group due to a greater atomic radius and increased amounts of shielding

melting point

the group 2 elements are metallic meaning the larger the ions within the metallic structure, the weaker the attractive forces as the attractive force has to act over a much greater distance. Therefore the melting point decreases going down the group

reactions with water

The group two elements react with water in a redox reaction to produce a metal hydroxide and hydrogen. The metal hydroxide form as an alkaline solution, hence why the group 2 metals are known as the alkali metals.

example of a reaction with water

magnesium reacts very slowly in this way with liquid water. However, the reaction can be much faster with steam as it provides the reaction with extra energy. When steam in used, the magnesium burns with a bright white flame to form hydrogen and magnesium oxide, a white powder.

equation of magnesium's reaction with steam

Solubility of hydroxides

the solubility of group 2 hydroxides varies and means these compounds have different uses. Solubility increases down the group meaning magnesium hydroxide is the least soluble and barium hydroxide the most soluble. As a result, magnesium hydroxide is used in medicine as an antacid as it is alkaline and can neutralise acids. It is used in a similar way in agriculture to neutralised acidic solids.

does solubility of sulphates increase or decrease down the group

decrease meaning magnesium sulphate is the most soluble and barium sulphate is the least soluble

Why is the insolubility of barium sulfate useful?

it means it is very useful in medicine such as barium meals. These are a form of medical tracer that allow internal tissues and organs to be imaged. Barium sulphate is toxic if it enters the blood stream, however because it is insoluble, it cannot be absorbed so it is safe to use in this way

what does barium chloride test for

sulphate ions as it reacts to for barium sulphate which forms a white precipitate when sulphate ions are present

what does magnesium help to extract

helps extract titanium from titanium chloride via a displacement reaction

what helps in flue gas removal

Calcium oxide reacts with sulphur dioxide to remove it from factory pollutants and prevent it from being released into the atmosphere. This forms calcium sulphite water