Grade 8
  1. Introduction to Chemistry  1.1. Nature and scope of chemistry  1.2. Importance of chemistry in daily life  1.3. Chemistry and its relation with other sciences  1.4. The role of chemistry in industry, medicine and the environment  1.5. Scientific investigation and experimental methods in chemistry
  2. Matter and its properties  2.1. Definition and classification of matter  2.2. Physical and chemical properties of matter  2.3. Law of conservation of matter  2.4. Extensive and Intensive Properties of Matter  2.5. Kinetic molecular theory of matter  2.6. States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates  2.7. Changes in state and energy are involved  2.8. Diffusion and Brownian motion
  3. Elements, Compounds, and Mixtures  3.1. Definition and differences between elements, compounds, and mixtures  3.2. Atomic Structure and Atomic Number  3.3. Chemical symbols and formulas  3.4. Trends in the Periodic Table (Groups and Periods)  3.5. Classification of Elements: Metals, Nonmetals and Metalloids  3.6. Rare Earth Elements and Transition Metals  3.7. Types of mixtures: homogeneous and heterogeneous  3.8. Separation of Mixtures Using Physical and Chemical Methods
  4. Separation Techniques  4.1. Filtration, Sedimentation and Decantation  4.2. Evaporation and crystallization  4.3. Distillation and Fractional Distillation  4.4. Chromatography and its applications  4.5. Sublimation in the purification of compounds  4.6. The role of centrifugation in biochemical processes
  5. Atomic Structure  5.1. Dalton's atomic theory  5.2. Structure of the atom: protons, neutrons and electrons  5.3. Bohr's atomic model  5.4. Introduction to Quantum Mechanical Model  5.5. Electron Configuration and Energy Levels  5.6. Excitation and emission spectra  5.7. Isotopes and their applications
  6. Periodic Table and Chemical Trends  6.1. History and Development of the Periodic Table  6.2. Modern periodic law  6.3. Periodicity and trends in atomic and ionic sizes  6.4. Ionization Energy, Electron Affinity and Electronegativity  6.5. Introduction to Lanthanides and Actinides  6.6. Application of periodic trends in chemistry
  7. Chemical Bonding and Molecular Structure  7.1. Types of chemical bonds: ionic, covalent and metallic bonds  7.3. Polar and Nonpolar Molecules  7.4. Hydrogen bonding and its applications  7.5. Intermolecular forces: dipole-dipole, London dispersion force
  8. Chemical Reactions and Stoichiometry  8.1. Chemical Equations and Balance  8.2. Types of Chemical Reactions: Combination, Decomposition, Displacement and Redox  8.3. Introduction to stoichiometry and the mole concept  8.4. Limiting reactant in chemical equations  8.5. Reaction rate, catalyst, and factors affecting reaction rate
  9. Acids, Bases and Salts  9.1. Definition and Properties of Acids and Bases  9.2. Strong vs. Weak Acids and Bases  9.3. pH Scale and pH Calculation  9.4. Neutralization reactions  9.5. Buffer solutions and their importance  9.6. Applications of Acids, Bases and Salts in Daily Life
  10. Solutions and Solubility  10.1. Definition of Solution, Solute, and Solvent  10.2. Factors Affecting Solubility  10.3. Concentration units: molarity and molality  10.4. Saturated, unsaturated and supersaturated solutions  10.5. Concept of osmosis and reverse osmosis  10.6. Concentrative properties of solutions
  11. Gases and Gas Laws  11.1. Properties of gases  11.2. Introduction to Ideal and Real Gases  11.3. Boyle's Law, Charles' Law and Avogadro's Law  11.4. Ideal Gas Equation and Its Applications  11.5. Application of Gas Laws in Real Life
  12. Thermochemistry and energy transformation  12.1. Energy in Chemical Reactions  12.2. Exothermic vs. Endothermic Reactions  12.3. Heat and Enthalpy Changes  12.4. Calorimetry and heat transfer in reactions
  13. Metals and Nonmetals  13.1. Physical and Chemical Properties of Metals and Nonmetals  13.2. Reactivity Series of Metals  13.3. Corrosion and its prevention  13.4. Extraction of metals from ores  13.5. Uses of metals and non-metals in daily life
  14. Introduction to Organic Chemistry  14.1. Characteristics of carbon and organic compounds  14.2. Functional groups and their importance  14.3. Simple Hydrocarbons: Alkenes, Alkenes and Alkynes  14.4. Isomerism in organic compounds  14.5. Introduction to polymers and their uses
  15. Environmental Chemistry and Sustainability  15.1. Green Chemistry Principles  15.2. Effects of Chemical Pollution on Ecosystems  15.3. Acid rain and its effects  15.4. Ozone layer depletion and global warming  15.5. Waste Management and Recycling in Chemistry

Grade 8 → Matter and its properties ↓


Definition and classification of matter


Matter is all around us. From the air we breathe to the solid ground we walk on, everything is made of matter. Understanding what matter is and how it is classified is a fundamental concept in chemistry. Matter can be defined as anything that has mass and occupies space. This definition implies that matter has two basic properties: mass and volume. Mass is the amount of matter present in an object, while volume is the space the object occupies.

Properties of matter

Matter is characterized by both physical and chemical properties.

  • Physical properties: These are properties of a substance that can be seen or measured without causing any change in the substance. Examples include color, melting point, boiling point, density, and state (solid, liquid, gas).
  • Chemical properties: These define the ability of a substance to undergo a chemical change, meaning that the substance will turn into a completely new substance. Examples include reactivity with oxygen (like iron rusting), acidity or alkalinity, combustibility, etc.

States of matter

Matter can exist in many states, the most common of which are solid, liquid, and gas. Let's take a closer look:

Solids

The particles in solids are very closely packed together. This arrangement gives solids a definite shape and volume. For example, a diamond maintains its shape whether it is in your hand or in a jewelry box. The particles in solids vibrate in place but do not move around freely.

Liquids

The particles in liquids are close together but not in any fixed position. This causes them to flow and take the shape of their container, although the volume remains constant. The water in a glass can be poured into another container and it will take on the new shape but will occupy the same amount of space.

Gases

The particles in gases are far apart and move freely in all directions. This means that gases can expand to fill their container. This feature is why a balloon inflates: the gas expands until it completely fills the balloon.

Classification of matter

Matter is broadly classified into two categories: mixtures and pure substances. Let's learn about them.

Mixture

A mixture is a combination of two or more substances where each substance retains its chemical identity. Mixtures can be classified into homogeneous and heterogeneous mixtures.

  • Homogeneous mixtures: These are completely uniform, meaning you cannot see or distinguish the individual components. An example of this is salt dissolved in water; once mixed, you cannot see the individual salt particles. These are often referred to as solutions. Other examples include air and steel.
  • Heterogeneous mixtures: These are not uniform, and in many cases, you can see or distinguish the individual components. Examples include a salad, a bowl of cereal with milk, or oil and water, where the oil floats on top of the water.

Pure Substance

Pure substances have a definite or fixed composition. They can be elements or compounds.

  • Elements: These are substances that cannot be broken down into simpler substances. Elements contain only one type of atom and are found in the periodic table. Examples include gold (Au), hydrogen (H), and oxygen (O).
  • Compounds: Compounds are substances that are formed when two or more elements are chemically joined together. Compounds have properties that are different from their individual elements. For example, water (H2O) is a compound made of hydrogen and oxygen.

Chemical formulas and equations

Chemical formulas represent substances using the symbols of their constituent elements. For example, the chemical formula for water is H2O, which indicates that it consists of two hydrogen atoms bonded to one oxygen atom.

Chemical equations show the reactions between substances that turn them into different substances. An example is the combustion of methane:

CH4 + 2O2 → CO2 + 2H2O

This equation shows that one molecule of methane reacts with two molecules of oxygen to form one molecule of carbon dioxide and two molecules of water.

Changes in matter

Physical and chemical changes can occur in matter.

  • Physical changes: These changes do not change the identity or composition of a substance. Examples include ice melting, sugar dissolving in water, or cutting a sheet of paper. The original substances can often be recovered by physical means.
  • Chemical changes: In chemical changes, substances change into new substances with different composition. For example, burning wood, rusting of iron or baking a cake, where new substances are formed.

Conclusion

Understanding matter and its classification helps us understand the physical world. Understanding how matter can exist in different states and forms, and how it can change, forms the foundation of chemistry and other sciences. Whether we are mixing ingredients in the kitchen or testing reactions in the laboratory, the principles of matter work in countless ways, emphasizing its importance in the natural world.


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Definition and classification of matter

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