Chemical Bonding and Molecular Structure

Why do atoms bond at all? This chapter — the longest in NCERT Class 11 — answers that question from every angle. You'll start with the Kossel-Lewis octet rule, learn how electrovalent (ionic) bonds form and how lattice enthalpy controls their stability, then move to covalent bonding through Lewis structures, formal charge, resonance, and the limitations of the octet rule. From there, you'll master the parameters that describe a bond (length, angle, enthalpy, order, polarity, dipole moment), predict molecular shapes using VSEPR, and understand the underlying physics through Valence Bond Theory, hybridization (sp, sp$^2$, sp$^3$, sp$^3$d, sp$^3$d$^2$), and Molecular Orbital Theory. The chapter closes with hydrogen bonding — the unsung hero behind ice floating, DNA's double helix, and water's life-supporting properties. This is THE foundation chapter for the rest of inorganic and organic chemistry, so invest the time. JEE and NEET pull 2-3 questions from it every single year.