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 → Elements, Compounds, and Mixtures ↓


Classification of elements


Understanding the classification of elements is important in grade 7 chemistry as it forms the basis for learning about chemical reactions and understanding the basic nature of matter. In this guide, we will explore elements, compounds and mixtures and how they fit into the world around us. We will look at each category in depth, highlighting their properties and giving examples to make these concepts easier to understand.

Elements

Elements are pure substances that cannot be broken down into simpler substances by chemical means. Each element is unique and is represented on the periodic table. The periodic table is an organized chart that displays all known elements based on their atomic numbers, chemical properties, and electron configurations.

Examples of elements: - Oxygen (O) - Hydrogen (H) - Carbon (C) - Nitrogen (N)
Hydrogen Oxygen Carbon

Elements are made up of identical atoms. For example, a sample of the element gold is made up entirely of gold atoms. Each gold atom has the same number of protons in its nucleus, making it unambiguously gold. This atomic structure is what defines an element.

Compounds

While elements are pure substances containing only one type of atom, compounds are made up of molecules formed by the chemical combination of two or more different types of atoms. The properties of a compound differ from those of the elements that make it up.

Examples of compounds: - Water (H2O) - Carbon Dioxide (CO2) - Table Salt (Sodium Chloride, NaCl) - Methane (CH4)
H O H

The formula for water, H2O, shows that it is composed of two hydrogen atoms and one oxygen atom. These atoms bond chemically to form water, a compound with very different properties from hydrogen and oxygen gases.

Mixture

A mixture consists of two or more substances physically combined, with each substance retaining its original chemical properties. Mixtures can be homogeneous or heterogeneous, depending on how evenly the substances are distributed.

Homogeneous mixture

Homogeneous mixtures (or solutions) have the same composition. An example of this is salt dissolved in water. The salt is evenly distributed in this mixture, making every sip taste the same.

Examples of homogeneous mixtures: - Saltwater - Sugar dissolved in water - Air (a mixture of gases)
salt water Air

Heterogeneous mixtures

Heterogeneous mixtures have different areas where the composition varies. For example, a salad is a heterogeneous mixture because different bites can contain different amounts of ingredients.

Examples of heterogeneous mixtures: - Sand and iron filings - Salad - Oil and water
Salad sand and iron

Distinguish between elements, compounds, and mixtures

Keep these key points in mind to distinguish between elements, compounds, and mixtures:

  • Element - Made of one type of atom, having specific and similar properties.
  • Compounds - are composed of molecules made up of different types of atoms chemically bonded, and have properties that differ from their constituent elements.
  • Mixtures - Two or more substances are physically combined, where each substance retains its own properties. They can be either homogeneous or heterogeneous.

The importance of understanding the basics of chemistry

Understanding these basic concepts in chemistry is essential for in-depth study in science. Understanding elements, compounds, and mixtures not only helps in academic success but also helps in appreciating the nature of materials encountered in everyday life. It lays the foundation for understanding various natural phenomena and technological processes.

In conclusion, the classification of substances into elements, compounds, and mixtures enhances our ability to understand and predict the behavior of substances, thereby promoting advances in science and technology. With this understanding, students can explore the world of chemistry with curiosity and confidence, ready to tackle more complex concepts in their educational journey.


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Classification of elements

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