Grade 7
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Scientific Method in Chemistry  1.5. Laboratory Safety Rules and Precautions  1.6. Common Laboratory Equipment and Their Uses  1.7. Units of measurement in chemistry
  2. Matter and its properties  2.1. Definition of Matter  2.2. Classification of matter  2.3. Properties of matter  2.3.1. Physical properties  2.3.2. Chemical properties  2.4. States of matter  2.4.1. Solid state  2.4.2. Fluid state  2.4.3. Gaseous state  2.4.4. Plasma and Bose–Einstein condensates  2.5. Changes in the states of matter  2.5.1. Melting and freezing  2.5.2. Evaporation and Condensation  2.5.3. Sublimation and deposition  2.6. Density and its applications  2.7. Diffusion and its importance
  3. Elements, Compounds, and Mixtures  3.1. Definition of the element  3.2. Classification of elements  3.3. Metals, Nonmetals and Metalloids  3.4. Noble gases and their properties  3.5. Introduction to the Periodic Table  3.6. Definition of Compound  3.7. Properties of Compounds  3.8. Introduction to Chemical Formulas  3.9. Definition of Mixture  3.10. Types of mixtures  3.10.1. Homogeneous mixture  3.10.2. Heterogeneous mixtures  3.11. Difference Between Compounds and Mixtures  3.12. Solutions, Colloids and Suspensions
  4. Separation of mixtures  4.1. Need for separation of mixtures  4.2. Separation methods  4.2.1. Filtration  4.2.2. Sedimentation and decantation  4.2.3. Evaporation  4.2.4. Crystallization  4.2.5. Distillation  4.2.6. Chromatography  4.2.7. Magnetic Separation  4.2.8. Centrifugation
  5. Atomic Structure  5.1. Introduction to Atoms  5.2. Structure of the atom  5.2.1. Nucleus and electron cloud  5.3. Subatomic particles  5.3.1. Proton  5.3.2. Neutron  5.3.3. Electrons  5.4. Atomic number and mass number  5.5. Isotopes and their uses  5.6. Ions and ion formation
  6. Periodic table  6.1. Introduction to the Periodic Table  6.2. Groups and periods  6.3. Trends in the Periodic Table  6.3.1. Atomic Size  6.3.2. Metallic and non-metallic character  6.3.3. Electronegativity  6.3.4. Reactivity of the elements  6.4. Alkali metals and their properties
  7. Chemical bond  7.1. Why do atoms form bonds?  7.2. Types of chemical bonds  7.2.1. Ionic bond  7.2.2. Covalent bond  7.2.3. Metal Bond  7.3. Properties of Ionic and Covalent Compounds  7.4. Intermolecular forces
  8. Chemical reactions  8.1. Introduction to Chemical Reactions  8.2. Signs of a chemical reaction  8.3. Types of Chemical Reactions  8.3.1. Combination Reactions  8.3.2. Decomposition reactions  8.3.3. Displacement reactions  8.3.4. Double displacement reactions  8.3.5. Combustion reactions  8.4. Law of conservation of mass  8.5. Balancing simple chemical equations
  9. Acids, Bases and Salts  9.1. Definition of Acid and Base  9.2. Properties of Acids  9.3. Properties of bases  9.4. pH Scale and Indicators  9.5. Neutralization reactions  9.6. Common Acids and Bases in Everyday Life  9.7. Preparation and use of salts  9.8. Strong and weak acids and bases
  10. Solutions and Solubility  10.1. Definition of Solution  10.2. Components of the solution  10.2.1. Solvent  10.2.2. solute  10.3. Factors Affecting Solubility  10.4. Concentration of solutions  10.5. Saturated and unsaturated solutions  10.6. Colloids and suspensions  10.7. Solubility curve and its interpretation
  11. Air and atmosphere  11.1. Composition of air  11.2. Properties of gases in the air  11.3. Importance of Oxygen and Carbon Dioxide  11.4. Air pollution and its effects  11.5. Greenhouse effect and global warming  11.6. Ways to reduce air pollution  11.7. Ozone layer and its importance
  12. Water and its importance  12.1. Properties of Water  12.2. Water as the universal solvent  12.3. Importance of water for life  12.4. Water pollution and its effects  12.5. Water Purification  12.5.1. Filtration  12.5.2. boil  12.5.3. Chlorination in water purification  12.5.4. reverse osmosis  12.6. Hard and soft water  12.7. Water cycle and its importance
  13. Fuel and energy  13.1. Types of fuel  13.1.1. Fossil fuels  13.1.2. Renewable energy sources  13.2. Combustion and energy release  13.3. Global warming and its effects  13.4. Alternative sources of energy  13.5. Ways to conserve energy
  14. Metals and Nonmetals  14.1. Physical and chemical properties of metals  14.2. Physical and Chemical Properties of Non-Metals  14.3. Difference Between Metals and Nonmetals  14.4. Uses of metals and nonmetals  14.5. Corrosion of metals and its prevention  14.6. Alloys and their importance
  15. Plastics and polymers  15.1. Natural and synthetic polymers  15.2. Properties of plastics  15.3. Biodegradable and Non-Biodegradable Plastics  15.4. Environmental impact of plastic  15.5. Recycling and waste management in plastics and polymers  15.6. Daily Uses of Polymers
  16. Introduction to Organic Chemistry  16.1. Basic definitions of organic chemistry  16.2. Carbon Compounds in Daily Life  16.3. Hydrocarbons  16.4. Simple functional groups (alcohols and carboxylic acids)  16.5. Importance of organic compounds in industry

Grade 7 → Chemical reactions ↓


Types of Chemical Reactions


Chemistry is a fundamental part of science that deals with how different substances interact. An important aspect of this is understanding chemical reactions. A chemical reaction is a process in which substances, known as reactants, are transformed into different substances, called products. In this ultra-detailed explanation designed specifically for the Grade 7 level, we will explore the different types of chemical reactions in a simple and clear way.

What is a chemical reaction?

A chemical reaction occurs when two or more substances come together and create new substances with different properties. During this process, the bonds between atoms in the reactants are broken, and new bonds are formed to create products. An important thing to remember is that matter is never actually created or destroyed in a chemical reaction. This concept is known as conservation of mass.

Types of chemical reactions

In chemistry, there are several basic types of chemical reactions. Understanding these helps us predict how different substances will behave when they interact. The main types include:

  1. Synthesis reactions
  2. Decomposition reactions
  3. Single displacement reactions
  4. Double displacement reactions
  5. Combustion reactions

Synthesis reactions

Synthesis reactions occur when two or more simple substances combine to form more complex substances. You can think of it as building a larger structure from smaller building blocks. The general equation for a synthesis reaction can be written as:

A + B → AB

For example, when hydrogen gas reacts with oxygen gas, water is formed. This can be represented as:

2H 2 + O 2 → 2H 2 O

Visual example:

In the visual example above, the blue circle and the red circle combine to form a purple circle, which represents the synthesis reaction.

Decomposition reactions

A decomposition reaction is the opposite of a synthesis reaction. In it, a single compound breaks down into two or more simpler substances. The general equation for a decomposition reaction is:

AB → A + B

For example, when water is electrolyzed, it breaks down into hydrogen and oxygen gases:

2H 2 O → 2H 2 + O 2

Visual example:

Here, the purple circle is split into a blue circle and a red circle, indicating the decomposition reaction.

Single displacement reactions

In a single displacement reaction, one element in a compound replaces another element. This type of reaction is often represented as:

A + BC → AC + B

A common example is when zinc metal reacts with hydrochloric acid to displace hydrogen gas:

Zn + 2HCl → ZnCl 2 + H 2

Visual example:

In this image, the gray circle switches places with the blue rectangle, forming a compound on the right, indicating a single displacement reaction.

Double displacement reactions

A double displacement reaction occurs when parts of two compounds switch partners. Its general form is:

AB + CD → AD + CB

An example of a double-displacement reaction is when silver nitrate reacts with sodium chloride to form silver chloride and sodium nitrate:

AgNO 3 + NaCl → AgCl + NaNO 3

Visual example:

Here, the reactants rearrange their partners to form new products on the right, visually representing a double displacement reaction.

Combustion reactions

Combustion reactions are a type of reaction in which a substance combines with oxygen and releases a significant amount of energy in the form of light and heat. Most combustion reactions involve hydrocarbon compounds. The general equation for the complete combustion of a hydrocarbon is:

C x H y + O 2 → CO 2 + H 2 O

The combustion of methane gas is a common example:

CH 4 + 2O 2 → CO 2 + 2H 2 O

Visual example:

The example above shows gray fuel (the reactant) reacting with red oxygen to produce gray carbon dioxide and water vapor as products.

Conclusion

Understanding the different types of chemical reactions is important to understanding broader concepts in chemistry. Each reaction type has its own characteristics and results, but they all follow the same basic principles of rearranging atoms to form new substances. Recognizing these reactions helps predict the outcomes of chemical interactions, which is important in everything from creating new materials to understanding natural processes.


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Types of Chemical Reactions

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