Lesson Notes By Weeks and Term - Senior Secondary 3

TERM׃ I^ST TERM

WEEK ONE

Class: Senior Secondary School 3

Age: 17 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Chemistry

Topic: Metals and their Compounds 1

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

1. Explains the general characteristics of metals.
2. Identify parts of the periodic table containing metals.

iii. Show on charts the relative abundance of metals in nature.

1. Describe the extraction processes of metals
2. Identify the general properties of alkali metals.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: i.  samples of metals and their compounds.
ii. periodic table of elements.
iii. charts of mineral ore distribution in Nigeria. 

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher explains the characteristics of metals	Students pay attention
STEP 2 EXPLANATION	Teacher guide students to identify parts of the periodic table contain metals	Students pay attention and participate
STEP 3 DEMONSTRATIO N	Teacher discusses using diagrams the principles of extraction of metals.	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 1

Chemical characteristics of metals

Metals exhibit several chemical characteristics:

1. Metals tend to lose electrons easily, leading to the formation of positively charged ions (cations). This property is linked to their position on the left side of the periodic table.
2. Metals share a common bonding characteristic called metallic bonding, where electrons are delocalized and move freely among metal atoms. This accounts for their conductivity and malleability.
3. Metals undergo oxidation reactions, where they lose electrons. The ease with which a metal loses electrons is related to its reactivity. Highly reactive metals, like alkali metals, oxidize readily.
4. Metals combine with nonmetals to form ionic compounds. The metal donates electrons to the nonmetal, resulting in the formation of positively charged metal ions and negatively charged nonmetal ions..
5. Metals generally react with acids to produce hydrogen gas and form salts. The reactivity varies among metals, with some reacting more vigorously than others.

Compounds of Metals

Metals form a wide variety of compounds with nonmetals. Below are some common types:

1. Metal Oxides: Metals react with oxygen to form metal oxides. For example, the reaction of iron with oxygen produces iron oxide (rust).

    4Fe + 3O₂  2Fe₂O₃

2. Metal Hydroxides: Metals react with water to form metal hydroxides. Sodium reacts with water to produce sodium hydroxide and hydrogen gas.

   2Na + 2H₂O  2NaOH + H₂

3. Metal Chlorides: Metals often react with chlorine to form metal chlorides. For example, sodium reacts with chlorine to produce sodium chloride.

  2Na + Cl₂ 2NaCl

4. Metal Sulfides: Metals combine with sulfur to form metal sulfides. An example is the formation of zinc sulfide.

   Zn + S  ZnS

5. Metal Carbonates: Metals react with carbonate ions to form metal carbonates. For instance, calcium reacts with carbonate ions to produce calcium carbonate.

   Ca²⁺ + CO₃^2-   CaCO₃

Principles of extraction of metals

1. Electrolysis: Electrolysis is a method used for the extraction of certain metals, especially those that are more reactive and cannot be easily reduced by conventional methods like smelting.
2. Reduction of oxides: The principle of reducing metal oxides involves the removal of oxygen from the metal compound to obtain the pure metal. This process typically employs carbon (in the form of coke or carbon monoxide) as a reducing agent. For example, in the reduction of iron;

Fe₂O₃ + 3C 2Fe + 3CO₂

3. Reduction of chloride

Metal extraction through the reduction of chlorides involves using a reactive metal, typically sodium or magnesium, to displace the metal from its chloride. This process is known as the "reactive metal extraction" method. For example, in the reduction of titanium;

 TiCl₄ + 2Mg  2MgCl₂ + Ti

4. Reduction of sulphate

The reduction of metal sulfates involves using a more reactive metal to displace the metal from its sulfate, a process known as the "metal displacement" or "thermite" reaction.

For example, in the extraction of iron:

FeSO₄ + Al Al₂SO₄  +  Fe

Alkali Metals

Alkali metals, found in Group 1 of the periodic table, share several general properties:

1. Alkali metals have a soft texture and a shiny, metallic appearance.
2. They exhibit low density compared to other metals.
3. Alkali metals generally have low melting and boiling points, making them relatively easy to melt and evaporate.
4. They are good conductors of heat and electricity.

5: Alkali metals are highly reactive due to their tendency to lose the outermost electron easily, forming positive ions.

6. Alkali metals readily form ionic compounds with non-metals, especially halogens.

Sodium

Extraction of sodium

Sodium is primarily extracted through the electrolysis of molten sodium chloride (NaCl) in a process known as the Downs Cell. The following are the key steps in the extraction of sodium:

1. Formation of Molten Sodium Chloride:

   - Common salt, sodium chloride (NaCl), is melted to form a molten salt.

2. Downs Cell Electrolysis:

   - The molten NaCl is electrolyzed in the Downs Cell, which consists of a container with a graphite anode and a molten sodium cathode.

3. Ion Migration:

   - When an electric current is passed through the molten NaCl, sodium ions migrate toward the cathode, gain electrons, and get reduced to form sodium metal.

 Na⁺ + e^-    Na

   - Chloride ions migrate toward the anode, lose electrons, and get oxidized to form chlorine gas.

 2Cl^- Cl₂ + 2e^-

4. Collection of Sodium:

   - Sodium, being less dense than the molten salt, rises to the surface and is collected.

5. Formation of Chlorine Gas:

   - Chlorine gas is evolved at the anode and can be collected separately.

Properties of sodium

Sodium possesses several notable properties:

1. Physical Properties:

   - Metallic Nature: Sodium is a soft, shiny, and silvery-white metal.

   - Density: It has a relatively low density.

   - Melting Point: Sodium has a low melting point of 97.8°C (208°F).

2. Chemical Properties:

   - Reactivity: Sodium is highly reactive, especially with water. It reacts vigorously, producing sodium hydroxide and hydrogen gas.

   - Oxidation States: It typically exhibits an oxidation state of +1 in compounds.

   - Formation of Compounds: Sodium readily forms compounds, including sodium chloride (table salt) and sodium hydroxide (a strong base).

3. Flame Test:

   - When sodium compounds are burned, they impart a yellow color to the flame.

Uses of sodium

Sodium has various industrial and everyday uses:

1. Chemical Industry:

   - Sodium Hydroxide (NaOH): Used in the production of soaps, detergents, and various chemicals.

   - Sodium Carbonate (Na₂CO₃): Commonly known as soda ash, it is used in the production of glass, paper, and textiles.

2. Metallurgical Applications: Sodium is used as a reducing agent in the extraction of certain metals, such as titanium and zirconium.
3. Water Treatment:

   - Sodium Hypochlorite (NaClO): Found in bleach and used as a disinfectant and water treatment chemical.

4. Food Industry:

   - Table Salt (Sodium Chloride, NaCl): Essential for flavoring and preserving food.

EVALUATION: 1. identify parts of the periodic table containing metals

2. Mention five characteristics of metals.
3. Identify 3 compound of metals.
4. Enumerate four uses of sodium.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively