Grade 9
  1. Matter and its nature  1.1. Introduction to matter  1.2. Physical and chemical properties of matter  1.3. States of matter  1.3.1. Solid state  1.3.2. Fluid state  1.3.3. Gaseous state  1.3.4. Plasma and Bose–Einstein condensate  1.4. Changes in the states of matter  1.4.1. Melting and freezing  1.4.2. Evaporation and Condensation  1.4.3. Sublimation and deposition  1.5. Classification of matter  1.6. Elements, Compounds, and Mixtures  1.7. Pure substances and impurities  1.8. Separation Techniques  1.8.1. Filtration  1.8.2. Distillation  1.8.3. Crystallization  1.8.4. Chromatography  1.8.5. Centrifugation  1.8.6. Sublimation  1.8.7. Decantation and sedimentation
  2. Atomic Structure  2.1. Discovery of atoms  2.2. Dalton's atomic theory  2.3. Structure of the atom  2.4. Subatomic particles  2.5. Atomic number and mass number  2.6. Isotopes and Isobars  2.7. Electronic configuration  2.8. Bohr's atomic model  2.9. Modern Atomic Model (Quantum Mechanical Model - Introduction)  2.10. Valency and chemical bonding
  3. C hemical reactions and equations  3.1. Introduction to Chemical Reactions  3.2. Chemical Equation Formulation  3.3. Balancing Chemical Equations  3.4. Types of Chemical Reactions  3.4.1. Combination Reactions  3.4.2. Decomposition reactions  3.4.3. Displacement reactions  3.4.4. Double displacement reactions  3.4.5. Redox reactions  3.4.6. Endothermic and Exothermic Reactions  3.5. Effects of chemical reactions  3.6. Energy Changes in Chemical Reactions  3.7. Catalysts and their role in reactions
  4. Periodic table and periodicity  4.1. History of Periodic Classification  4.2. Mendeleev's periodic table  4.3. Modern Periodic Table  4.4. Periods and groups in the periodic table and periodicity  4.5. Trends in the Periodic Table  4.5.1. Atomic size  4.5.2. Ionization Energy  4.5.3. Electron affinity  4.5.4. Electronegativity  4.5.5. Metallic and Non-Metallic Properties  4.6. Noble gases and their properties
  5. Chemical bond  5.1. Introduction to Chemical Bonding  5.2. Types of chemical bonds  5.2.1. Ionic bond  5.2.2. Covalent bond  5.2.3. Metallic bond  5.2.4. Hydrogen bonding  5.2.5. Van der Waals force  5.3. Properties of Ionic and Covalent Compounds  5.4. Molecular Structure and Geometry (VSEPR Theory - Basics)
  6. Acids, Bases and Salts  6.1. Introduction to Acids and Bases  6.2. Properties of Acids  6.3. Properties of bases  6.4. pH scale and its importance  6.5. Indicators and their uses  6.6. Neutralization reactions  6.7. Strength of Acids and Bases (Strong vs. Weak)  6.8. Preparation of salts  6.9. Uses of acids, bases and salts in daily life
  7. Metals and Nonmetals  7.1. Physical Properties of Metals  7.2. Physical Properties of Nonmetals  7.3. Chemical properties of metals  7.4. Chemical Properties of Nonmetals  7.5. Reactivity Series of Metals  7.6. Extraction of metals  7.7. Corrosion and its prevention  7.8. uses of metals and nonmetals
  8. Carbon and its compounds  8.1. Introduction to Carbon  8.2. Allotropes of carbon (diamond, graphite, fullerene)  8.3. Hydrocarbons  8.3.1. Hydrocarbons  8.3.2. Alkene  8.3.3. Alkynes  8.4. Functional groups in organic chemistry  8.5. Isomerism in organic compounds  8.6. Alcohols and Carboxylic Acids  8.7. Soaps and detergents  8.8. Polymers (Introduction to Natural and Synthetic Polymers)
  9. Solutions and Mixtures  9.1. Types of mixtures  9.2. Homogeneous and Heterogeneous Mixtures  9.3. Concentration of solutions  9.4. Solubility and factors affecting solubility  9.5. Suspensions and Colloids  9.6. Saturated, unsaturated and supersaturated solutions
  10. Air and atmosphere  10.1. Composition of air  10.2. Role of gases in the atmosphere  10.4. Acid rain and its effects  10.5. Greenhouse effect and global warming  10.6. Ozone layer and its depletion  10.7. Air pollution control measures
  11. Water and its importance  11.1. Composition and properties of water  11.2. Hardness of water (temporary and permanent hardness)  11.3. Causes of water pollution  11.4. Effects of Water Pollution  11.5. Water purification methods (filtration, boiling, chlorination)
  12. Industrial Chemistry  12.1. Introduction to Industrial Chemistry  12.2. Important industrial chemicals (sulfuric acid, ammonia, sodium hydroxide)  12.3. Chemical processes in industry  12.4. Uses of Industrial Chemistry in Daily Life  12.5. Environmental impact of industrial chemical processes

Grade 9 → Metals and Nonmetals ↓


Physical Properties of Metals


Metals are a fundamental class of substances in chemistry and physics. They are characterized by their unique physical properties, which make them incredibly useful for a variety of applications in everyday life and industrial processes. In this detailed exploration, we will discuss several key physical properties of metals that contribute to their unique behavior and uses.

1. Glitter

One of the most notable physical properties of metals is their shiny appearance. This shiny characteristic, known as lustre, is due to the ability of metals to reflect light. The electrons in metals are able to move around freely, and this mobility allows metals to efficiently absorb and re-emit photons of light. This makes metals appear shiny and lustrous.

Examples of luster in metals:

  • Gold used in jewellery has a yellow metallic lustre.
  • Silver is often used in cutlery and mirrors, and has a white lustre.
  • Copper used in electrical wiring exhibits a reddish-brown lustre.
Sleep Silver Copper

2. Conductivity

Metals are exceptionally good conductors of electricity and heat. This property arises due to the presence of free electrons in the metal structure. In metals, electrons can move freely in the lattice structure, which allows them to transport electric current efficiently. Similarly, these electrons can transfer heat energy quickly.

For example:

  • Copper is widely used in electrical cables due to its excellent conductivity.
  • For this reason aluminum is often used in overhead power lines.
Electrons

3. Flexibility

Malleability is the ability of a metal to be hammered or rolled into thin sheets without breaking. This is due to the ability of the atoms in the metal lattice to slide over each other without breaking. Malleability is an important property that allows metals to be formed into various shapes.

Examples of malleability in metals:

  • Gold can be beaten into extremely thin sheets called gold leaf.
  • Aluminium is used to make foil and beverage cans.
Thin metal sheet

4. Flexibility

Ductility refers to the ability of metals to be drawn into wires. Like malleability, ductility is a result of the bonds in the metal that allow atoms to move past one another. The more ductile the metal, the easier it is to be drawn into wires.

Examples of ductility in metals:

  • Copper wires are widely used in electrical wiring.
  • Steel wires are used in construction work and to reinforce concrete.
Metal Wire

5. Density

Density is defined as the mass per unit volume of a substance. Most metals have a high density because the atoms in metals are tightly packed together in a lattice structure. The density of metals can vary depending on the type. For example, lead and gold are very dense, while aluminum is relatively less dense.

Some typical densities (measured in grams per cubic centimeter or g/cm3):

  • Lead: 11.34 g/cm3
  • Gold: 19.32 g/cm3
  • Aluminum: 2.70 g/cm3
Denser Metal Less Dense

6. Melting point and boiling point

Metals generally have high melting and boiling points. This is because the metallic bonds that hold the atoms together are strong and require a lot of energy to break. However, there are some variations among metals. For example, mercury is a metal that is liquid at room temperature.

Examples of melting points of some metals:

  • Iron: 1538°C
  • Copper: 1085°C
  • Mercury: -38.83°C (liquid at room temperature)

7. Rigidity

Hardness is a measure of how resistant a metal is to deformation or scratching. Different metals exhibit different levels of hardness. Generally, transition metals are harder than alkali metals. For example, the amount of carbon in steel can substantially change its hardness.

Examples of hard metals:

  • Alloys made from tungsten and diamond are extremely hard.
  • Steel, which is an alloy of iron, is much harder than pure iron.

8. Strength

Strength refers to the ability of a metal to withstand an applied force without breaking or deforming. Most metals have a high tensile strength, which is why they are widely used in construction and manufacturing.

Examples of strong metals:

  • Steel is used in the construction of structures and bridges.
  • Titanium is known for its strength-to-weight ratio, making it ideal for aerospace applications.

Conclusion

Metals, with their unique physical properties, play a vital role in a wide variety of fields, from industrial applications to daily life. Their lustre makes them attractive for jewellery, conductivity makes them essential for electronics, and their ductility, tensile strength and strength make them ideal for construction and manufacturing. Understanding these properties helps us appreciate the value and utility of metals in our modern world.


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Physical Properties of Metals

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