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 → Atomic Structure ↓


Subatomic particles


Subatomic particles are the building blocks of atoms, the smallest units of matter. Atoms combine to form molecules, which in turn form everything we see around us, from the air we breathe to the tools we use. Understanding subatomic particles is fundamental to exploring the world of chemistry and physics.

What are subatomic particles?

Subatomic particles are particles that are smaller than atoms. They include three main types: protons, neutrons, and electrons. Each type of subatomic particle has different properties and functions, yet they all combine to form atoms.

Types of subatomic particles

  • Protons: These are positively charged particles found in the nucleus of an atom. The number of protons in the nucleus of an atom determines which element the atom belongs to. For example, an atom with one proton is hydrogen, while an atom with six protons is carbon.
  • Neutrons: Neutrons are neutral particles, meaning they have no charge. They are also found in the nucleus of an atom. Neutrons play an important role in holding the nucleus together, preventing it from falling apart due to the repulsion force between the protons.
  • Electrons: These are negatively charged particles that orbit the nucleus of an atom. Electrons are much smaller than protons or neutrons. They are responsible for the chemical behaviour of atoms as they are involved in forming chemical bonds between atoms.

Structure of the atom

An atom consists of a nucleus, which contains protons and neutrons, and an electron cloud that orbits around the nucleus. The nucleus is much smaller than the entire atom but contains nearly all of its mass. The electron cloud is much larger, but the electrons are so light that they contribute very little to the atom's overall mass.

Visual example: Atomic structure

Nucleus Electron Electron Proton/Neutron

Role of subatomic particles in elements

Each element in the periodic table has a specific number of protons, known as the atomic number. This atomic number defines the element:

Hydrogen: 1 proton Helium: 2 protons Lithium: 3 protons
Hydrogen: 1 proton Helium: 2 protons Lithium: 3 protons

In addition to protons, the number of neutrons and electrons may vary. The total number of protons and neutrons in the nucleus of an atom determines its atomic mass. Electrons are equal to the number of protons in a neutral atom so that the positive charge is balanced with the negative charge.

Ions: Charged particles

Sometimes atoms gain or lose electrons, resulting in charged particles called ions. When an atom loses electrons, it becomes positively charged and is called a cation. When an atom gains electrons, it becomes negatively charged and is called an anion. For example:

Na → Na⁺ + e⁻ Cl + e⁻ → Cl⁻
Na → Na⁺ + e⁻ Cl + e⁻ → Cl⁻

In the above reactions, sodium (Na) loses an electron to form a positive ion (Na⁺), while chlorine (Cl) gains an electron to form a negative ion (Cl⁻).

How subatomic particles affect chemical reactions

The interactions of subatomic particles, especially electrons, play an important role in chemical reactions. Electrons can be shared or transferred between atoms to form chemical bonds. Here are some types of bonds based on electron interactions:

  • Covalent bonds: These are formed when atoms share electrons. A common example of this is the bonding of two hydrogen atoms to form a hydrogen molecule (H2).
  • Ionic bonds: These are formed when electrons are transferred from one atom to another, creating an attraction between ions with opposite charges. An example of this is the formation of sodium chloride (NaCl).

Understanding these interactions helps us to form compounds and determine their properties.

Visual example: Covalent bond

H H

Subatomic particles and isotopes

An isotope is a form of an element that has the same number of protons but a different number of neutrons. Isotopes can have different physical properties while still maintaining the same chemical properties. For example:

Carbon-12: 6 protons, 6 neutrons Carbon-14: 6 protons, 8 neutrons
Carbon-12: 6 protons, 6 neutrons Carbon-14: 6 protons, 8 neutrons

Although both are isotopes of carbon, carbon-14 is radioactive and is used in dating ancient artifacts, while carbon-12 is stable.

Visual example: Isotopes

C-12 C-14

Conclusion

Understanding subatomic particles is essential to understanding the concept of atomic structure, elements, and chemical reactions. Protons, neutrons, and electrons each have their own unique role in defining the identity and behavior of atoms. They are the foundation of chemistry, and knowing how they work allows us to understand more complex scientific phenomena.

Delving further into the world of chemistry, keep in mind that these tiny particles hold the secrets of everything from the materials that make up the universe to the atoms in our bodies. Every discovery in the subatomic realm continues to shape our understanding of the natural world.


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Subatomic particles

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