Alkaline Earth Metals, Aluminium And Tins SS3 Chemistry Lesson Note

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. list and explain the general properties of alkali earth metals.
2. Discuss the extraction, properties and uses of calcium.
3. Discuss the extraction, properties and uses of aluminium. 

INSTRUCTIONAL TECHNIQUES: 

• Identification, 
• explanation, 
• questions and answers,
• demonstration, 
• videos from source

NOTE

The alkali earth metals

Group 2A (IIA) of the periodic table are alkaline earth metals. They include elements like beryllium, magnesium, calcium, strontium, barium, and radium. They share similar properties, such as high melting points and low densities.

Extraction of Calcium

Calcium is primarily extracted from its ores(limestone CaCO3, gypsum and anhydrite, dolomite or fluorspar)  through a process called electrolysis, where calcium chloride is electrolyzed to obtain calcium metal. Another method involves the reduction of calcium oxide (lime) with aluminium, resulting in the production of calcium and aluminium oxide.

Properties of calcium

1. Physical Properties:

• Silvery-white, somewhat malleable metal.
•  Fairly hard and has a density higher than most other elements.

2. Chemical Properties:

•   Reacts vigorously with water to produce calcium hydroxide and hydrogen gas.
• Forms compounds with various elements, and it readily reacts with oxygen and nitrogen in the air.

3. Biological Importance:

• Vital for living organisms, contributing to bone and teeth structure.
• Essential for nerve transmission, muscle function, and blood clotting.

Other properties include;

• Burns with a distinctive red flame when heated.
• It is a good conductor of electricity.

Compounds of calcium

Calcium forms various compounds. Some notable ones include:

1. Calcium Carbonate (CaCO₃):Abundant in nature as limestone, marble, and chalk.
2. Calcium Chloride (CaCl₂):Often used as a drying agent, de-icer, and in food preservation.
3. Calcium Hydroxide (Ca(OH)₂):Commonly known as slaked lime; used in construction (mortar) and as a pH regulator.
4. Calcium Oxide (CaO):Also known as quicklime; used in cement production and various industrial processes.

Uses of calcium

1. Calcium compounds like limestone and gypsum are used in the construction industry for making cement, mortar, and plaster.
2. Calcium is essential for the formation and maintenance of bones and teeth.
3. Crucial for nerve transmission, muscle function, and blood clotting in living organisms.
4. Calcium is used as a reducing agent in the extraction of some metals from their ores.
5. Calcium chloride is used as a desiccant to absorb moisture in various applications.
6. Calcium hydroxide is used in water treatment to adjust pH and remove impurities.
7. Calcium supplements are used to address calcium deficiencies in the human body.
8. Calcium is essential for plant growth, and calcium-containing fertilisers are used to improve soil quality.

Extraction of Aluminum

The extraction of aluminium is primarily done through the Hall-Héroult process. The following are the key steps for the extraction of aluminium:

1. Bauxite Mining: Bauxite, an aluminium ore, is mined from the Earth. It typically contains various impurities.
2. Bauxite Refining: The bauxite is processed to extract alumina (aluminium oxide) through the Bayer process. Alumina is then obtained from the bauxite ore.
3. Alumina Reduction: In the Hall-Héroult process, alumina is dissolved in molten cryolite (a mineral) at high temperatures (around 950°C).
4. Electrolysis: The dissolved alumina is electrolyzed in a carbon-lined cell. An electric current is passed through the molten mixture, causing aluminium ions to be reduced and deposited as molten aluminium at the cathode.
5. Collection of Aluminum: The molten aluminium, being less dense than the molten cryolite, floats to the top of the cell and is collected.

Uses of Aluminum

1. Aluminium is widely used in the aerospace industry for aircraft construction. Commonly used in the automotive industry for lightweight vehicle components.

1. Aluminium foil and containers are extensively used in food packaging due to their lightweight and corrosion-resistant properties.
2. Used in the construction industry for doors, windows, and structural components due to its strength and corrosion resistance.
3. Aluminium is commonly used in the production of cookware and kitchen utensils due to its excellent heat conductivity.
4. Used in medical equipment and prosthetics due to its biocompatibility and corrosion resistance.

EVALUATION:   

1. Identify alkali earth metals.

1. Mention three compounds of calcium.
2. Discuss the extraction of aluminium.
3. Enumerate 4 uses of aluminium.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively