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 ↓


Noble gases and their properties


Introduction to noble gases

Noble gases are a group of chemical elements with similar properties. These elements are in group 18 of the periodic table. Noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). These gases are colorless, odorless, tasteless, and non-flammable under standard conditions.

Characteristics of noble gases

A unique property of the noble gases is that they are very little reactive. This means that they do not easily form compounds with other elements. This lack of reactivity is because they have full outer shells of electrons, making them very stable. For example, helium has two electrons in its outer shell, which is filled, while the other noble gases have eight electrons.

He 2 electrons

Why are noble gases nonreactive?

To understand why the noble gases are unreactive, we need to look at electron shells. Electrons are arranged in layers called "shells" around the atom's nucleus. Atoms are more stable when their outer shells are full. Most atoms gain, lose, or share electrons to achieve a full outer shell and become stable.

The noble gases already have naturally complete outer electron shells. The lack of need to gain, lose, or share electrons makes them very stable and unreactive. For example, Neon has an electron configuration of 2, 8; it does not need any more electrons. Its outer shell is complete.

Daily uses of noble gases

Although the noble gases are nonreactive, they have many important uses:

  • Helium: It is used in balloons and airplanes because it is lighter than air and non-flammable.
  • Neon: It is used in neon signs for advertising because it gives off a bright glow when an electric current is passed through it.
  • Argon: It is used to prevent the tungsten filament in light bulbs from reacting with oxygen.

Visual examples of noble gases

Helium filled balloons

Helium is commonly used to fill balloons. Since helium is lighter than air, helium-filled balloons float.

More interesting facts about noble gases

Although the noble gases are generally unreactive, they can form compounds under certain conditions. Scientists have been able to form compounds with krypton, xenon, and radon under specific laboratory conditions. However, these are rare and not usually found naturally.

Another interesting property is that some noble gases can produce light when electric current is passed through them. This property is used in lighting and advertising. For example, when electricity passes through neon, it emits a bright red-orange light, which is widely used in neon lights.

Compounds and mixtures containing noble gases

Difference between elements, compounds and mixtures

Before discussing compounds and mixtures involving noble gases, it is important to understand the differences:

  • An element is a substance that is made up entirely of one type of atom. The noble gases are good examples of pure elements.
  • A compound is a substance made up of two or more different types of atoms. The noble gases rarely form compounds, but some exceptions exist.
  • A mixture consists of two or more substances mixed together but not chemically combined. Noble gases may be part of a mixture but retain their individual properties.

Scientific notation of noble gases

Let's explore the scientific notation used to describe the noble gases, focusing on helium and neon as examples:

Helium (He): Atomic number 2, Electron configuration = 1s²
Neon (Ne): Atomic number 10, Electron configuration = 1s² 2s² 2p⁶

Role of noble gases in the atmosphere

Noble gases make up a very small portion of the Earth's atmosphere, but they play a very important role. For example, argon makes up about 0.93% of the atmosphere and is important in providing an inert atmosphere for welding.

Conclusion: Understanding the noble gases

In short, the noble gases are a fascinating group of elements with unique properties. Their full electron shells make them unreactive, yet they have meaningful applications in everyday life, from providing buoyancy to balloons to helping illuminate neon signs. Understanding the noble gases provides insight into the wider world of chemistry and the components that make up our universe.


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Noble gases and their properties

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