Group 2

describe the trend in atomic radius

The atomic radius increases down the group due to more shielding making the atomic radius bigger

Describe the trend in melting points

The melting points decrease down the group this is because the atomic radius increases and therefore the distance between positive ions and delocalised electrons increase and so the electrostatic attraction between the positive ions and delocalised electrons weaken, metallic bonding

Describe the trend in ionisation energy

The ionisation energy decreases down the group because of the increased shielding increasing the atomic radius, this means the outer electron is further away from the nucleus making the electrostatic attraction weaker and making it easier to remove the outer electron.

describe the trend of reactivity

increases down the group

What happens in a reaction between Magnesium and Oxygen

MgO and H2 is produced, Mgo is a white solid, burns with a white flame

What happens in a reaction between group 2 metals and water

• a metal hydroxide and H2 is produced

• fizzing occurs and gets more vigorous down the group

• calcium hydroxide forms a white precipitate as it doesnt dissolve

What happens when Magnesium reacts with steam

• MgO and H2 is produced

• white solid

How is Magnesium used to extract Titanium

TiO2 + 2Cl2 + 2C -→ TiCl4 + 2CO (900degrees)

TiCl4 + 2Mg -→ Ti + 2MgCl2 (500degrees)

why cant titanium be extracted using carbon

Because it would form Titanium carbide which cannot be extracted by electrolysis

why is Titanium expensive

• The Mg needed is expensive

• It is a batch process which means it is slow to produce and requires more labour and energy

• high temperatures needed

• argon needed to remove moisture

Trend of solubility of Group 2 hydroxides

the solubility increases down the group where magnesium hydroxide is classed as insoluble in water

What is calcium hydroxide used for

In agriculture to neutralise acidic soils

What is Magnesium Hydroxide used for

It is used in medicine to neutralise excess stomach acid to help with constipation

Trend of solubility of Group 2 sulphates

The solubility decreases down the group, BaSO4 is the least soluble

What is BaSO4 also known as and used for

It is known as Barium meal and is used to x ray the small intestine and the gut, the patient will swaller the barium meal and it will show up on the x ray. The solubility means it wont be absorbed into the blood

How to test the presence of a sulfate ion

• acidified BaCl2 is the reagent for testing for sulfate ions

• a white precipitate is a positive result

• the BaCl2 must be acidified with HCl to react with carbonate ions and H2SO4 cant be used as it would produce a false positive result.

• fizzing would occur of carbonate ions are present

What is flue gas removal

When Calcium oxide is used to react with Sulfur dioXide to remove it from factory pollutants, forms calcium suLfate and water

CaO + 2H2O + SO2 -→ CaSO3 + 2H2O