JEE Main and Advanced:

Shortcut Methods and Tricks:

1. Periodic Trends:

• Electronegativity: Increases across a period and decreases down a group.
• Ionization Energy: Increases across a period and decreases down a group.
• Atomic Radii: Increases down a group and decreases across a period.

2. Types of Bonds:

• Ionic Bonds: Large electronegativity difference (≥1.7).
• Polar Covalent Bonds: Moderate electronegativity difference (0.4-1.7).
• Nonpolar Covalent Bonds: Small electronegativity difference (≤0.4).

3. Bond Formation:

• Bonds form when atoms achieve a lower potential energy state by sharing or transferring electrons.
• The number of bonds formed is determined by the valence electrons of the atoms involved.

4. Electronegativity Difference:

• The greater the electronegativity difference, the more polar the covalent bond.

5. Bond Enthalpies:

• Stronger bonds have higher bond enthalpies.
• Factors influencing bond strength: bond order, atomic sizes, and presence of multiple bonds.

6. Coordinate Covalent Bonds:

• One atom provides both electrons for the bond.
• Common in complexes and ligands.

7. Lewis Dot Structures:

• Represent molecules and ions by showing the arrangement of valence electrons and the formation of bonds.
• Follow the octet rule and minimize formal charges.

CBSE Board Exams:

Shortcut Methods and Tricks:

1. Ionic and Covalent Bonds:

• Ionic bonds have an electronegativity difference ≥1.7.
• Covalent bonds have an electronegativity difference ≤1.7.

2. Electron Sharing:

• Covalent bonds involve the sharing of electron pairs between atoms.

3. Bond Length and Bond Angle:

• Bond length: shorter bond corresponds to a stronger bond.
• Bond angle: determined by the geometry of the molecule (e.g., tetrahedral, octahedral).

4. Lewis Dot Symbols:

• Represent the valence electrons of atoms as dots around the atomic symbol.

5. Polarity of Covalent Bonds:

• Polar covalent bonds are formed when two atoms have very close and nearly equal electronegativities.

6. Electronegativity:

• Electronegativity is the ability of an atom to attract electrons.

7. Metallic Bonding:

• Electrons become delocalized and free to move in a metallic lattice, leading to electrical conductivity and thermal conductivity.