Class 9th · Chemistry · Chapter 3
Chapter 3: Chemical Bonding
Chapter 3 of the Punjab Board Class 9th Chemistry textbook runs from page 36 to 55. Its exercise has exercise. Open any of those pages in GenZ Books, tap a question, and the answer is worked from this chapter.
Open Chapter 3 of Chemistry in GenZ Books
The same Class 9th textbook, page for page. Tap any question and get the answer worked from that chapter — English and Urdu.
What you will learn
- Describe that noble gas electronic configuration, octet and duplet rules help predict chemical properties of main group elements
- Compare between the formation of cations and anions Account for the electropositive and electronegative nature of metals and non-metals
- Define ionic, covalent, coordinate covalent and metallic bonds
- Differentiate between ionic compounds and covalent compounds. (The following points need to be included in the respective definitions: a. lonic Bond as strong electrostatic attraction between oppositely charged ions b. Covalent bond as strong electrostatic attraction between shared electrons and two nuclei c. Metallic bond as strong electrostatic attraction between cloud/sea of delocalized electrons and positively charged cations)
- Explain the properties of compounds in terms of bonding and structure
- Compare uses and properties of materials such as strength and conductivity as determined by the type of chemical bond present between their atoms
- Interpret the strength of forces of attraction and their impact on melting and boiling points of ionic and covalent compounds
- Justify the availability of free char
Exercise
- Exercisep. 53
A sample answer from GenZ Books
Explain · page 50: 3.8 Nature of Bonding and Properties
The way atoms bond together dictates the physical properties of the substances you see around you every day. Nature of Bonding and Properties (بانڈنگ کی نوعیت اور خصوصیات) connects the microscopic type of chemical bond holding a substance together to its macroscopic traits like melting points, electrical conductivity, and hardness.
- Melting and Boiling Points: Ionic compounds (آئنیک مرکبات) have high melting and boiling points because strong electrostatic forces hold their ions tightly in a crystal lattice (क्रিস্টل لیٹیس), requiring a lot of heat energy to break.
- Electrical Conductivity: Ionic compounds do not conduct electricity in solid form because ions are fixed, but they conduct electricity in the molten state (پگھلی ہوئی حالت) or in aqueous solution when ions become free to move.
- Solubility: Ionic solids are generally soluble in water because polar water molecules pull the ions apart and surround them in a process called hydration (ہائیڈریشن).
- Brittleness: Crystal lattices are brittle (بھُر بھُرا) because applying an external force shifts ions of the same charge next to each other, causing repulsion and breaking the crystal.
Think of building a brick wall in your neighborhood: if you stack bricks tightly using strong cement, the wall is very solid and hard to break (like an ionic crystal lattice), but if a sudden heavy push shifts the alignment so that matching forces face each other, the whole section snaps apart cleanly rather than bending.
A common mistake is thinking that ionic compounds can conduct electricity in their solid form because they contain charged ions; remember that ions must be free to move (either melted or dissolved in water) to carry an electrical current.
Higher-tier chemistry shows that these exact lattice energies and hydration energies can be calculated precisely using thermodynamics.
In short: The strong electrostatic forces in ionic crystal lattices create stable solids that are brittle, have high melting points, and conduct electricity only when molten or dissolved.
AI-generated from the chapter text by GenZ Books. It can make mistakes — check it against your textbook and your teacher.