Lesson Notes By Weeks and Term - Senior Secondary 3

TERM׃ I^ST TERM

WEEK TWO

Class: Senior Secondary School 3

Age: 17 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Chemistry

Topic: Metals and their Compounds 2

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.

iii.  Discuss the extraction, properties and uses of aluminium. 

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, periodic table of elements.

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher introduces alkali earth metals and indicate their position on the periodic table.	Students pay attention
STEP 2 EXPLANATION	Teacher discuss the extraction, properties and uses of calcium.	Students pay attention and participate
STEP 3 DEMONSTRATIO N	Teacher discusses the extraction, properties and uses of  aluminium.	Students pay attention and participate
STEP 4 NOTE TAKING	The teacher writes a summarized note on the board	The students copy the note in their books

 

NOTE

METALS AND THEIR COMPOUNDS 2

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 aluminum, resulting in the production of calcium and aluminum 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.

   - Crucial for nerve transmission, muscle function, and blood clotting in living organisms.

3. Calcium is used as a reducing agent in the extraction of some metals from their ores.
4. Calcium chloride is used as a desiccant to absorb moisture in various applications.
5. Calcium hydroxide is used in water treatment to adjust pH and remove impurities.
6. Calcium supplements are used to address calcium deficiencies in the human body.
7. Calcium is essential for plant growth, and calcium-containing fertilizers are used to improve soil quality.

Extraction of Aluminum

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

1. Bauxite Mining: Bauxite, an aluminum ore, is mined from the Earth. It typically contains various impurities.
2. Bauxite Refining: The bauxite is processed to extract alumina (aluminum 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 aluminum ions to be reduced and deposited as molten aluminum at the cathode.
5. Collection of Aluminum: The molten aluminum, being less dense than the molten cryolite, floats to the top of the cell and is collected.

Uses of Aluminum

1. Aluminum is widely used in the aerospace industry for aircraft construction.

 Commonly used in the automotive industry for lightweight vehicle components.

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

EVALUATION:   1. Identify alkali earth metals.

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

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively