| sharing of electrons- covalent bond formed between | two electropositive elements |
| hypovalent species vs hypervalent species | sharing ke baad 8 e se kam vs. sharing ke baad 8 e se jyada |
| instances of failure of law of octet | 1. H
2. hypo and hypervalent
3. odd e- mol.
4. inert gases forming compounds |
| concepts (2) in valence bond theory | concept of overlapping
concept of hybridization |
| concept of overlapping | based on energy minimization tendency of a system- not octet |
| benefit of overlapping | e- cloud do nucleus ke command mein hain
- attraction increases
- energy further decreases
therefore bond more stable |
| overlapping continues till | a sweet spot of maximum energy is reached |
| axial vs collateral overlapping in s-s vs p-p | axial- internuclear axis ke along
collateral- internuclear axis ke upar neeche |
| covalent molecule- only ... filled molecules overlap | half filled |
| overlapping orbitals should have... symmetry | same symmetry ++ or --
not +- ....apavitra rishta SUM 0 |
| FAILURE OF overlapping | failed to explain poluatomic molecules like- CH4
- all symmetrical even though one 2s1s and other three 2p1s
- all bond angle and bond length same(shouldnt be acc to overlapping) |
| launch of hybridisation | redistribution of energy- hybrid orbitals- to explain polyatomic mol.
- poly at mol- hybridisation ke baad hi overlap hota hai |
| hybridisation defn | when orbitals of diff energies intermix and redistribute their energies to form orbitals of similar energy
its called hybridisation
and new orbitals - hybrid orbitals |
| type of hyb.= | no of surrounding atoms + no of lone pairs on the central atom |
| ....bonds are longer and weaker than ....bonds | axial weaker than equitorial |
| ,....(a/e) feel more repn and whY? | each eq. bond is repelled by three axial bonds while each axial bond is repelled by three equitorial bonds
- axial bonds feel more repn.
- BS dec, and BL inc |
| in case of sp3d- lone pairs are always plced at...a/e | equitorial positon |
| BP- BP vs LP BP vs LP LP repn comparision
- vsepr explains | <<
- bond angle and shape of molecules |
| LP should always be placed at a/e | equitorial |
| in ether bond(ROR) angle b/n two R-R groups is... and why | 110 deg
greater than b/w two lp cuz of steric hindrance
same with ncl3 and NBr3 |
| pi bond should be kept on ...(a/e) | equitorial to minimize pi-pi or sigma-pi repulsion |
| why SiO2 has different structure from CO2 | sp3 in SiO2 vs sp in CO2
cuz co2 small discrete molecule while silica a giant lattice |
| why N2O5 gas has different hybridisation than its solid? | gas- covalent bonds
solid ionic bonds |
| ....- .... repulsion is the strongest | pi pi |
| why benzene all bonds of equal size | resonance |
| types of resonance | 8 types |
| bent rule no 1- more electroneg. atom is placed at ...(a/e) | axial |
| bond angle reln to EN of surrounding atoms | INVERSELY PROPORTIONAL |
