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 → Chemical bond ↓


Types of chemical bonds


Chemical bonds are an essential concept in chemistry that explains how atoms join together to form molecules and compounds. Atoms bond with each other in different ways depending on how they share or exchange their electrons. Chemical bonds are the forces that hold atoms together and enable them to function as a unit. Understanding these bonds is important because it helps us explain how different substances form and why they have specific properties. In this detailed explanation, we'll explore the different types of chemical bonds, including ionic bonds, covalent bonds, metallic bonds, and hydrogen bonds.

Ionic bond

Ionic bonds form when electrons are transferred from one atom to another. This usually occurs between metals and nonmetals. Metals lose electrons and become positively charged ions called cations, while nonmetals gain electrons and become negatively charged ions called anions.

For example, in the formation of sodium chloride (NaCl), sodium (Na), which is a metal, loses an electron to become the Na+ ion. Chlorine (Cl), which is a nonmetal, gains an electron to become the Cl− ion. The opposite charges of the ions attract each other, resulting in an ionic bond.

Na → Na+ + e-
Cl + e- → Cl-
Na+ + Cl- → NaCl

Here's a simple diagram to help you understand the ionic bond between sodium and chlorine:

Na Cl

Covalent bonds

Covalent bonds are formed when two or more nonmetal atoms share electrons. These bonds can be polar or nonpolar depending on the electronegativities of the atoms involved.

Non-polar covalent bond

Nonpolar covalent bonds occur when the electrons are shared equally between the atoms. An example of a nonpolar covalent bond is in the molecule of hydrogen gas (H2).

H + H → H2

Polar covalent bond

Polar covalent bonds form when electrons are shared unequally. This happens when one atom is more electronegative than the other. Water (H2O) is a common example of a molecule with a polar covalent bond.

H2 + O → H2O

Here is a simplified diagram to show the covalent bond in a water molecule:

O H H

Metal bond

Metallic bonds are unique because they occur between metal atoms. In this bond type, electrons are not shared or transferred with other atoms. Instead, they form a "sea of electrons" that flows freely in the metal lattice.

This "sea of electrons" allows metallic materials to conduct electricity and heat very efficiently and gives metals their characteristic shiny appearance.

Here's a diagram to show the sea of electrons in a metallic bond:

Metal Metal Metal Metal Metal Metal Electrons

Hydrogen bonds

Hydrogen bonds are quite different from other types of bonds. They form when a hydrogen atom, covalently bonded to a more electronegative atom such as oxygen, nitrogen or fluorine, experiences a force of attraction toward another electronegative atom. Hydrogen bonds are not as strong as covalent or ionic bonds, but they are very important in the structure of water and biological molecules such as DNA and proteins.

Here is an example of hydrogen bonding in water molecules:

O H H O H H Hydrogen bond

Conclusion

Understanding the different types of chemical bonds is vital to the study of chemistry and the properties of matter. Each type of bond – ionic, covalent, metallic and hydrogen – has unique properties that affect the behavior of molecules. Ionic bonds are formed by the transfer of electrons, covalent bonds are formed by the sharing of electrons, metallic bonds are formed by a sea of electrons and hydrogen bonds are formed by the weak attraction between molecules. These bonds come together to explain the complex world of molecules and compounds that make up the matter in the world around us.


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Types of chemical bonds

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