Chemical Bonding
Chemistry · रासायनिक बंधन
📋Quick Overview
Chemical bonding is the force that holds atoms together in molecules and compounds. Atoms bond to achieve a stable electronic configuration (complete octet — 8 electrons in outermost shell, or duplet for H and He). The main types are: Ionic bond (transfer of electrons), Covalent bond (sharing of electrons), and Metallic bond (sea of electrons).
📖Types of Chemical Bonds
| Bond Type | How Formed | Between | Example | Strength |
|---|---|---|---|---|
| Ionic | Transfer of electrons from metal to non-metal | Metal + Non-metal | NaCl, MgO, CaF₂, KCl | Strong |
| Covalent | Sharing of electron pairs between atoms | Non-metal + Non-metal | H₂O, CO₂, CH₄, NH₃, O₂ | Moderate to strong |
| Metallic | Electrons shared among all metal atoms (electron sea) | Metal + Metal | All metals: Fe, Cu, Au, Ag | Variable |
| Hydrogen Bond | Weak attraction between H and F/O/N of another molecule | H bonded to F, O, or N | Water (H₂O), DNA, Ice | Weak |
| Van der Waals | Very weak temporary attraction between molecules | All molecules | Noble gases, non-polar molecules | Very weak |
📖Ionic vs Covalent Compounds
📖Covalent Bond Types
| Type | Electron Pairs Shared | Bond | Example |
|---|---|---|---|
| Single Bond | 1 pair (2 electrons) | σ (sigma) | H-H, H-Cl, C-C in ethane |
| Double Bond | 2 pairs (4 electrons) | 1σ + 1π | O=O, C=O in CO₂, C=C in ethene |
| Triple Bond | 3 pairs (6 electrons) | 1σ + 2π | N≡N, C≡C in ethyne (acetylene) |
📝Special Points
- •Hydrogen bonding makes water a liquid at room temperature (otherwise H₂O would be a gas like H₂S)
- •Ice floats on water because H-bonds make ice less dense than liquid water
- •Diamond = covalent network solid (hardest natural substance). Graphite = layers with weak van der Waals forces (soft, conducts electricity)
- •Coordinate bond (Dative bond) = one atom donates both electrons. Example: NH₄⁺, H₃O⁺
- •Metallic bonding explains why metals are good conductors, malleable, and ductile