Chemistry Of Group 2 Elements

Reactivity towards halogen, sulphate, and carbonates

Group 2 elements are also known as alkaline earth metals
They include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra)
These elements have similar chemical properties due to their outermost electron configuration
Reactivity of Group 2 elements towards halogens, sulphates, and carbonates is an important topic in inorganic chemistry

Reactivity towards Halogens

Group 2 elements react with halogens to form ionic compounds
The reactivity increases down the group
Example: Reaction between magnesium and chlorine
- Mg + Cl₂ → MgCl₂
The combination of Group 2 elements with halogens is an exothermic reaction
The chlorides, bromides, and iodides of Group 2 elements are all white solids

Reactivity towards Sulphates

Group 2 elements can react with sulphates to form sulphates of alkaline earth metals
The reaction is generally a precipitation reaction
Example: Reaction between calcium and sulphate ion
- Ca²⁺ + SO₄²⁻ → CaSO₄
The solubility of metal sulphates decreases down the group

Reactivity towards Carbonates

Group 2 elements react with carbonates to form carbonates of alkaline earth metals
The reaction produces a gas (carbon dioxide)
Example: Reaction between barium and carbonate ion
- Ba²⁺ + CO₃²⁻ → BaCO₃ + CO₂
The solubility of metal carbonates decreases down the group
The carbonates of Group 2 elements are generally white solids

Solubility Trend in Hydroxides

Group 2 elements form hydroxides when reacted with water
The solubility of hydroxides increases down the group
Example: Solubility trend of Group 2 hydroxides
- Be(OH)₂ is amphoteric and has low solubility
- Mg(OH)₂ is insoluble and forms a white precipitate
- Ca(OH)₂ is sparingly soluble in water
- Sr(OH)₂ is slightly soluble in water
- Ba(OH)₂ is moderately soluble in water

Acid-base Behavior

Group 2 elements are relatively basic due to their tendency to lose two electrons
Their hydroxides can neutralize acids, forming salts and water
Example: Reaction of calcium hydroxide with sulfuric acid
- Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
The strength of the base increases down the group

Thermal Stability of Carbonates

Group 2 carbonates decompose upon heating
The thermal stability of carbonates increases down the group
Example: Thermal decomposition of magnesium carbonate
- MgCO₃ → MgO + CO₂
The decomposition temperature increases with the size of the cation

Lattice Energy and Ionic Radii Relationship

The lattice energy of alkaline earth metal compounds decreases down the group
This is due to the increase in ionic radii down the group
Lattice energy is the energy released when a solid ionic compound is formed from its constituent ions in the gas phase
The decrease in lattice energy results in the decrease in the stability of compounds down the group

Uses of Alkaline Earth Metals

Beryllium is used in the aerospace industry for its lightweight and high tensile strength
Magnesium is used in alloys, pyrotechnics, and as a reducing agent in the production of metals
Calcium is used in the production of cement, in the reduction of other metals, and as an alloying agent
Strontium is used in fireworks to produce red color and in producing glass for television tubes
Barium is used in medical imaging as a contrast agent and in the manufacture of ceramic and glass products
Radium has limited uses due to its radioactivity and high toxicity "

Slide 11:

The reactivity of Group 2 elements towards halogens increases down the group.
They form ionic compounds with halogens.
Examples:
- Magnesium reacts with chlorine to form magnesium chloride: Mg + Cl₂ → MgCl₂
- Calcium reacts with bromine to form calcium bromide: Ca + Br₂ → CaBr₂
The combination of Group 2 elements with halogens is exothermic.
The halides of Group 2 elements are white solids.

Slide 12:

Group 2 elements can react with sulphates to form sulphates of alkaline earth metals.
The reaction is generally a precipitation reaction.
Example:
- Calcium reacts with sulphate ions to form calcium sulphate: Ca²⁺ + SO₄²⁻ → CaSO₄
The solubility of metal sulphates decreases down the group.
The sulphates are generally white solids.

Slide 13:

Group 2 elements react with carbonates to form carbonates of alkaline earth metals.
The reaction produces carbon dioxide gas.
Example:
- Barium reacts with carbonate ions to form barium carbonate and carbon dioxide gas: Ba²⁺ + CO₃²⁻ → BaCO₃ + CO₂
The solubility of metal carbonates decreases down the group.
The carbonates of Group 2 elements are white solids.

Slide 14:

Group 2 elements form hydroxides when reacted with water.
The solubility of hydroxides increases down the group.
Examples:
- Beryllium hydroxide (Be(OH)₂) is amphoteric and has low solubility.
- Magnesium hydroxide (Mg(OH)₂) is insoluble and forms a white precipitate.
- Calcium hydroxide (Ca(OH)₂) is sparingly soluble in water.
- Strontium hydroxide (Sr(OH)₂) is slightly soluble in water.
- Barium hydroxide (Ba(OH)₂) is moderately soluble in water.

Slide 15:

Group 2 elements are relatively basic due to their tendency to lose two electrons.
Their hydroxides can neutralize acids, forming salts and water.
Example:
- Calcium hydroxide reacts with sulfuric acid to form calcium sulfate and water: Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
The strength of the base increases down the group.

Slide 16:

Group 2 carbonates decompose upon heating.
The thermal stability of carbonates increases down the group.
Example:
- Magnesium carbonate decomposes into magnesium oxide and carbon dioxide upon heating: MgCO₃ → MgO + CO₂
The decomposition temperature increases with the size of the cation.

Slide 17:

The lattice energy of alkaline earth metal compounds decreases down the group.
This is due to the increase in ionic radii down the group.
Lattice energy is the energy released when a solid ionic compound is formed from its constituent ions in the gas phase.
The decrease in lattice energy results in the decrease in the stability of compounds down the group.

Slide 18:

Beryllium is used in the aerospace industry for its lightweight and high tensile strength.
Magnesium is used in alloys, pyrotechnics, and as a reducing agent in the production of metals.
Calcium is used in the production of cement, in the reduction of other metals, and as an alloying agent.
Strontium is used in fireworks to produce red color and in producing glass for television tubes.
Barium is used in medical imaging as a contrast agent and in the manufacture of ceramic and glass products.
Radium has limited uses due to its radioactivity and high toxicity.

Slide 19:

Group 2 elements react with halogens to form ionic compounds.
The reactivity increases down the group.
Example: Reaction between magnesium and chlorine
- Mg + Cl₂ → MgCl₂
The combination of Group 2 elements with halogens is an exothermic reaction.
The chlorides, bromides, and iodides of Group 2 elements are all white solids.

Slide 20:

Group 2 elements can react with sulphates to form sulphates of alkaline earth metals.
The reaction is generally a precipitation reaction.
Example: Reaction between calcium and sulphate ion
- Ca²⁺ + SO₄²⁻ → CaSO₄
The solubility of metal sulphates decreases down the group.

Slide 21:

The reactivity of Group 2 elements towards carbonates increases down the group.
They form carbonates of alkaline earth metals.
Examples:
- Calcium reacts with carbonate ions to form calcium carbonate: Ca²⁺ + CO₃²⁻ → CaCO₃
- Barium reacts with carbonate ions to form barium carbonate: Ba²⁺ + CO₃²⁻ → BaCO₃
The solubility of metal carbonates decreases down the group.
The carbonates of Group 2 elements are white solids.

Slide 22:

Group 2 elements react with acids to form salts and hydrogen gas.
Example: Reaction between magnesium and hydrochloric acid
- Mg + 2HCl → MgCl₂ + H₂
The reactivity of Group 2 elements towards acids increases down the group.
The reaction with water is a redox reaction, where the metal is oxidized and water is reduced.

Slide 23:

Group 2 elements have a lower ionization energy compared to Group 1 elements.
Ionization energy is the energy required to remove an electron from an atom or ion in the gas phase.
The ionization energy generally decreases down the group.
This is due to the increase in atomic size and shielding effect down the group.

Slide 24:

Beryllium is the lightest alkaline earth metal.
It has a high melting point, low density, and is highly toxic.
Beryllium is commonly used as an alloying agent in the production of lightweight materials.
Due to its toxicity, proper precautions must be taken when handling beryllium and its compounds.

Slide 25:

Magnesium is a versatile alkaline earth metal.
It is the lightest metal that can be used as a structural material.
Magnesium alloys have excellent strength-to-weight ratio and are used in aerospace and automotive industries.
Magnesium is also used in pyrotechnics, as a reducing agent, and in the production of metals like titanium.

Slide 26:

Calcium is an essential element for living organisms.
It plays a crucial role in forming and maintaining healthy bones and teeth.
Calcium is used in the production of cement, as a reducing agent in the extraction of other metals, and as an alloying agent.
Calcium compounds are also used in the manufacturing of glass, ceramics, and fertilizers.

Slide 27:

Strontium is known for its bright red flame color.
It is used in fireworks and pyrotechnics to produce red color.
Strontium compounds are also used in the production of glass for television tubes, as additives in ceramics and metals, and in medicine for bone imaging.

Slide 28:

Barium compounds are often used in medical imaging.
Barium sulfate is commonly used as a contrast agent in X-rays and CT scans to visualize the gastrointestinal tract.
Barium compounds are also used in the production of ceramic and glass products, as well as in the petroleum industry for drilling fluids.

Slide 29:

Radium is a highly radioactive and unstable element.
It is extremely rare and found in small amounts in uranium ores.
Due to its radioactivity and toxicity, radium has limited uses.
In the past, radium was used in luminous paints, but its use has been discontinued due to health concerns.

Slide 30:

The alkaline earth metals exhibit similar chemical properties due to their outermost electron configuration.
They have higher melting and boiling points compared to Group 1 elements.
Alkaline earth metals have a smaller atomic radius and higher ionization energy compared to alkali metals.
These elements are less reactive than Group 1 elements but still readily form ionic compounds with other elements.