SS3 Chemistry Revision and Examination for Second Term

Chemistry, as a subject, plays a vital role in understanding the world around us. For SS3 students preparing for their exams, a strong foundation in core concepts is essential. In this article, we will walk through the important topics for the second term, covering key areas like nuclear chemistry, molecular shapes, petroleum, and quantitative analysis. Each topic will be explained in detail, with examples and clear explanations that even novices can grasp. We’ll also provide revision questions to help solidify your understanding.

1. Resumption Test/Nuclear Chemistry

Keywords: Nuclear Chemistry, Nuclear Reactions, Radioactivity, Natural vs. Artificial Radioactivity.

Nuclear chemistry involves the study of nuclear reactions, radioactivity, and the properties of radioactive substances. It focuses on how atoms undergo changes in their nuclei. These changes lead to the emission of radiation, which is important in a variety of applications, such as medical treatments and nuclear power generation.

Nuclear Reactions vs. Chemical Reactions: Nuclear reactions involve changes in an atom’s nucleus, which can result in the emission of radiation or the formation of new elements. On the other hand, chemical reactions involve the rearrangement of electrons in the outer shell of atoms but do not affect the nucleus.

Types of Nuclear Reactions:

1. Fission: The splitting of a heavy nucleus into smaller nuclei, releasing energy. Example: Nuclear reactors.
2. Fusion: The merging of light nuclei to form a heavier nucleus, releasing energy. Example: The Sun.
3. Alpha decay, Beta decay, Gamma radiation: Types of radioactivity.

Radioactivity: Radioactivity is the emission of radiation from unstable atomic nuclei. It can be natural, occurring spontaneously in elements like uranium, or artificial, produced by human activities (such as in nuclear reactors).

Examples:

• Natural Radioactivity: Uranium, Thorium, Radon.
• Artificial Radioactivity: Cobalt-60, Iodine-131.

Revision Questions for Nuclear Chemistry:

1. Define nuclear chemistry.
2. How do nuclear reactions differ from chemical reactions?
3. What is radioactivity?
4. List and explain the types of nuclear reactions.
5. Differentiate between natural and artificial radioactivity.
6. Give examples of natural radioactivity.
7. What are the applications of nuclear chemistry?
8. What is nuclear fission?
9. Describe the process of nuclear fusion.
10. What are the dangers of radiation?

2. Shapes and Molecules

Keywords: Hybridization, Hybrid Orbitals, Molecule Formation.

Hybridization refers to the process by which atomic orbitals mix to form new hybrid orbitals. These hybrid orbitals influence the shapes of molecules. Understanding the concept of hybridization is essential to predicting how atoms bond together.

Types of Hybrid Orbitals:

1. sp Hybridization: Forms a linear molecule (180° bond angle). Example: BeCl2.
2. sp2 Hybridization: Forms a trigonal planar molecule (120° bond angle). Example: BF3.
3. sp3 Hybridization: Forms a tetrahedral molecule (109.5° bond angle). Example: CH4.

Formation of Hybrid Orbitals: Atoms with unpaired electrons in their orbitals can mix their atomic orbitals to form hybrid orbitals, which in turn, form bonds with other atoms, creating molecules with specific shapes.

Revision Questions for Shapes and Molecules:

1. What is hybridization in chemistry?
2. How does hybridization affect the shape of molecules?
3. Explain sp hybridization with an example.
4. What is the bond angle in an sp2 hybridized molecule?
5. Describe the formation of hybrid orbitals.
6. What is the molecular shape of methane (CH4)?
7. What type of hybridization does boron trifluoride (BF3) undergo?
8. Define sp3 hybridization.
9. How does hybridization explain the geometry of molecules?
10. What is the importance of hybridization in molecular bonding?

3. Petroleum and Crude Oil

Keywords: Crude Oil, Fractional Distillation, Petroleum Cracking, Refining.

Crude oil is a natural resource formed from the remains of ancient marine organisms. It is composed of hydrocarbons and other organic compounds, and it undergoes fractional distillation to separate the different components. The various products of crude oil include fuels like gasoline and diesel, as well as raw materials for the petrochemical industry.

Origin and Composition of Crude Oil: Crude oil originates from the remains of microscopic marine organisms, which are buried under layers of sediment over millions of years. The heat and pressure from these layers transform the organic material into crude oil.

Fractional Distillation of Crude Oil: This process involves heating crude oil to separate it into fractions based on boiling points. Lighter fractions like gasoline are collected at the top of the distillation column, while heavier fractions like bitumen are collected at the bottom.

Petroleum Cracking: Petroleum cracking is a process used to break down large hydrocarbon molecules into smaller, more valuable molecules like gasoline and diesel. This process involves heating the crude oil and using catalysts.

Economic Importance of Crude Oil: Crude oil is a critical resource, driving global economies through its use in transportation, industry, and energy production. In countries like Nigeria, crude oil is a major export, contributing significantly to the economy.

Revision Questions for Petroleum and Crude Oil:

1. What is crude oil?
2. How is crude oil formed?
3. Describe the process of fractional distillation.
4. What are the main products of fractional distillation?
5. Explain petroleum cracking.
6. Why is crude oil important to the global economy?
7. List the major crude oil reserves in the world.
8. Where are the major oil refineries located in Nigeria?
9. What are the environmental impacts of petroleum extraction?
10. How does petroleum contribute to energy production?

4. Quantitative Analysis/Volumetric Analysis

Keywords: Quantitative Analysis, Volumetric Analysis.

Quantitative analysis refers to techniques used to determine the concentration of a substance in a sample. Volumetric analysis is one such technique, where the volume of a solution required to react with a sample is measured to determine the concentration.

Revision Questions for Quantitative Analysis:

1. What is quantitative analysis in chemistry?
2. Define volumetric analysis.
3. What is the purpose of a titration in volumetric analysis?
4. How do you determine the concentration of a solution using volumetric analysis?
5. What are the common reagents used in volumetric analysis?
6. What is the role of indicators in titration?
7. Describe the process of acid-base titration.
8. How do you calculate the concentration of a solution from titration data?
9. Explain how volumetric analysis is used in determining the purity of a substance.
10. What is a standard solution?

5. Qualitative Analysis

Keywords: Qualitative Analysis, Starch, Reducing Sugars, Non-Reducing Sugars, Proteins, Fats and Oils.

Qualitative analysis is used to identify the components present in a sample. In chemistry, this involves testing for specific substances like starch, sugars, proteins, fats, and oils.

Revision Questions for Qualitative Analysis:

1. What is qualitative analysis in chemistry?
2. How do you test for starch in a sample?
3. What is the difference between reducing and non-reducing sugars?
4. How do you test for proteins in a sample?
5. How do you test for fats and oils?
6. What reagents are used to test for reducing sugars?
7. Explain how Benedict’s solution is used in qualitative analysis.
8. How do you test for the presence of fats in food?
9. What is the test for non-reducing sugars?
10. Why is qualitative analysis important in chemistry?

6. Open Day/Mid-Term Break

This is a non-academic period but provides a chance to relax and reflect on the term’s studies.

7. Revision and Examination Preparation

To prepare for the upcoming exams, review each topic covered in this guide. Practice solving problems, reviewing past exam questions, and using your textbook to deepen your understanding.