Group 2

How can group 2 hydroxides be prepared by?

the reaction of the metal oxide and water

How would you describe the solubility of the group 2 hydroxides?

only slightly soluble in water

What happens when a group 2 hydroxide dissolves in water?

dissociates to release the metal cation and the hydrodxide ions e.g.

The solubility of the hydroxides ... down the group. Therefore the formed solution contains ... OH^- ions and is ... alkaline

1) increases
2) more
3) more

If a solution is becoming more alkaline, is pH increasing or decreasing?

increasing

What is the use of Ca(OH)₂ and why do we use it?

used in agriculture, to neutralise acidic soils

What is the use of Mg(OH)₂ and CaCO₃ and why do we use them?

as ‘antacids’ in treating indigestion.

Which compounds are used as antacids to neutralise excess stomach acid?

Mg(OH)₂ and CaCO₃

Which compound is used in agriculture to neutralise acidic soils?

Ca(OH)₂

Do group 2 metals have high or low bp/mp and explain why

have high mp/bp due to strong metallic bonds in their giant metallic lattice structures

Can group 2 metals conduct electricity? Explain your answer

yes they can conduct electricity in both solid and liquid form (molten) due to the mobile delocalised electrons

Why are group 2 metals considered s-block elements?

highest energy electron is found in an s subshell / orbital

Write an equation that represents the 2nd ionisation energy of Mg

In the reaction, (picture) what would you expect to observe as this reaction takes place?

• fizzing

• solid dissolves

State and explain what would be different about the resulting solution if you were to replace calcium with barium

• solution has lower pH, calcium hydroxide is less soluble in water than barium hydroxide

• less OH- ions dissociated into the solution

Is the reaction of magnesium with water slow or fast?

very slow

State and explain the trend in reactivity of the group 2 metals with dilute HNO₃

• reactivity with nitric acid increases down the group

• because number of electron shells/ atomic radius increases

• shielding increases

• nuclear attraction decreases despite nuclear charge increasing

• ionisation energy decrease so it is easier to lose electrons

How do Group 2 elements form 2+ ions in redox reactions in terms of electron configuration?

Group 2 elements have an outer-shell electron configuration of Xs². They lose both outer-shell electrons (oxidation) to form 2+ ions

How do Group 2 elements (Mg → Ba) react with oxygen?

• React with oxygen to form metal oxides.

• Reactivity increases down the group.

• General equation: 2M + O₂ → 2MO

How do Group 2 elements (Mg → Ba) react with water?

• React with water to form metal hydroxides + hydrogen gas.

• Reactivity increases down the group.

• General equation: M + 2H₂O → M(OH)₂ + H₂

• Mg reacts very slowly with cold water, whereas Ba reacts rapidly.

How do Group 2 elements (Mg → Ba) react with dilute acids?

• React with dilute acids to form a salt + hydrogen gas.

• Reactivity increases down the group.

• Example: Mg + 2HCl → MgCl₂ + H₂

Explain the trend in reactivity of Group 2 elements down the group in terms of first and second ionisation energies.

• First and second ionisation energies decrease down the group.

• Atomic radius and electron shielding increase, weakening the attraction between the nucleus and outer electrons.

• Therefore, both outer electrons are lost more easily to form 2+ ions, so reactivity increases.

How do Group 2 oxides react with water, and what is the trend in alkalinity down the group?

• Group 2 oxides react with water to form metal hydroxides, producing alkaline solutions.

• General equation: MO + H₂O → M(OH)₂

• Alkalinity increases down the group (approximately pH 9–13) because the hydroxides become more soluble, releasing more OH⁻ ions.

• MgO reacts slowly, while BaO reacts readily.