chemical bonding

Question 1

vsepr theory

Answer 1

Valence Shell Electron Pair Repulsion (VSEPR) Theory. The idea of a correlation between molecular geometry and the number of valence electrons was first presented in 1940 by Sidgwick and Powell; however, in 1957, Ronald Gillespie In polyatomic molecules (i.e. molecules made up of three or more atoms), one of the constituent atoms is identified as the central atom to which all other atoms belonging to the molecule are linked. The total number of valence shell electron pairs decides the shape of the molecule.

Question 2

Ionic bond or electrovalent bond

Answer 2

-discovered by william kossel
- define as the electrostatic and attraction between positive and negative ions
- electrovalent bond
-non directional bond
-Ions formation
-complete transfer of electron
-metals have low ionization potential and electronegativity (loss => IA, IIA,IIIA)
-non metals have high energy and energy high electronegativity and electron affinity (gain=> VIA, VIIA, VA)
- for the formation of ionic compound released energy must be greater than added energy
-electronegativity is greater than 1.7 between two elements usually leads to an ionic bond
-the great attractive forces in the crystal lattice greatly reduce the energy of system there by making it
Stable
-it is essential for the formation of Ions and the ionic bond that the sum of energy is released in the second and third steps must be larger than what is required in first step

Question 3

Tricks

Answer 3

• soluble condition:
  • lattaice Energy < hydration Energy
• insoluble condition:
  • lattice energy > hydration energy
  -smaller the size larger will be lattice energy
  -