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 → Metals and Nonmetals ↓


Physical and Chemical Properties of Metals and Nonmetals


Metals and nonmetals are two broad categories of elements that we study in chemistry. Both have different physical and chemical properties that play a vital role in various fields, including industrial applications, biology, and environmental science. Let's explore these properties in detail, and explain what makes metals and nonmetals unique.

Physical properties of metals

Aura

Metals have a certain shine. This is known as lustre. They reflect light, making them look shiny and lustrous. This is why metals such as gold, silver and aluminium are used to make jewellery and decorative items.

Metal

Growability

Metals can be hammered or rolled into thin sheets. This property is called malleability. For example, aluminum can be rolled into thin sheets to make foil for wrapping food.

Flexible Sheet

Resilience

Metals can be drawn into thin wires, this property is called ductility. Copper wires are commonly used in electrical wiring because they are excellent conductors and can be easily drawn into wires.

Tensile Wire

Conductivity

Metals are good conductors of heat and electricity. The free electrons present in metals allow them to transfer energy efficiently. This makes metals essential in electrical circuits and cooking utensils.

Electric Current

Sweet

Metals produce a ringing sound when struck, which is called sonorous. Due to this property, metals like steel are used to make musical instruments like bells and cymbals.

Density and hardness

Most metals are dense and hard. They have compact structures and high atomic weights. This is why they are used in construction and tool making.

Chemical properties of metals

Reaction with water

Many metals react with water to form hydrogen gas. For example, sodium reacts vigorously with water:

2Na + 2H₂O → 2NaOH + H₂↑

This reaction produces sodium hydroxide and hydrogen gas. Such reactions are exothermic and release heat.

Reaction with oxygen

Metals react with oxygen to form metal oxides. For example, iron reacts with oxygen in moist air to form iron oxide, commonly known as rust:

4Fe + 3O₂ → 2Fe₂O₃

These reactions can result in corrosion of the metal.

Reaction with acids

Most metals react with acids to form hydrogen gas. For example, zinc reacts with hydrochloric acid to form zinc chloride and hydrogen:

Zn + 2HCl → ZnCl₂ + H₂↑

Electropositivity

Metals lose electrons to form positive ions or cations. This property is known as electropositivity. It is an important factor in the behaviour of metals in chemical reactions.

Physical properties of nonmetals

Condition and structure

Nonmetals can exist as solids, liquids, or gases at room temperature. For example, sulfur and carbon are solids, bromine is liquid, and oxygen is a gas.

Lack of shine

Nonmetals are not shiny; they are often dull. This is because they do not reflect light like metals do. For example, coal (a form of carbon) is black and does not shine.

Brittleness

Nonmetals are usually brittle in the solid state and break or shatter when struck. For example, sulfur crystals are fragile and break easily when struck.

Insulator

Nonmetals are poor conductors of heat and electricity. They act as insulators. For example, materials such as rubber and wood are used to cover electrical wires due to their insulating properties.

Chemical properties of nonmetals

Reaction with oxygen

Nonmetals react with oxygen to form nonmetal oxides, which are usually acidic. For example, sulfur dioxide is formed when sulfur is burned in oxygen:

S + O₂ → SO₂

This sulfur dioxide can further react with water to form sulfurous acid:

SO₂ + H₂O → H₂SO₃

Reaction with water

Some nonmetals react directly with water. However, some nonmetal oxides react with water to form acids. For example, carbon dioxide reacts with water to form carbonic acid:

CO₂ + H₂O → H₂CO₃

Electronegativity

Nonmetals gain electrons to form negative ions or anions. This property is known as electronegativity, which refers to the tendency to attract electrons during chemical reactions.

Visualizing the differences

Metal: Malleable, Ductile Nonmetals: Brittle

Applications of metals and nonmetals

The distinctive properties of metals and nonmetals make them suitable for a variety of applications:

Metals

  • Construction: Steel and aluminum are used for building structures because of their strength and durability.
  • Electronics: Copper and silver are used in circuits due to their high electrical conductivity.
  • Transportation: Metals such as steel are used in car bodies, ships, and airplanes because of their strength.

Non metallic

  • Insulation: Materials such as rubber are used as insulators in electrical applications.
  • Fertilizers: Nitrogen and phosphorus compounds are used in fertilizers to enhance plant growth.
  • Nonmetals: Nonmetals such as silicon are important in making semiconductors for electronics.

Conclusion

Understanding the physical and chemical properties of metals and nonmetals is fundamental to chemistry. Metals typically exhibit properties such as lustre, ductility, malleability, conductivity, and sound. In contrast, nonmetals are typically dull, brittle, and poor conductors of heat and electricity. These properties shape their use and reactivity, which play essential roles in a variety of technological and industrial applications. Knowing how metals and nonmetals behave helps us harness their unique capabilities for everyday uses, from construction and electronics to agriculture and beyond.


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