Structure and bonding : in homo- and heteronuclear molecules, including shapes of molecules (VSEPR Theory).
|No.of questions appeared||3||4||1||1||2||2||3||1||3||3||4|
1. The total number of lone pairs of electrons in I3–is:
2. The strength of pΠ-dΠ bonding in E–O (E = Si, P, S and C) follows the order
(a) Si – O > P – O > S – O >Cl – O
(b) P – O > Si – O > S – O >Cl – O
(c) S – O >Cl – O > P – O > Si – O
(d) Cl – O > S – O > P – O > Si – O
Smaller the inter nuclear distance between two atoms, stronger will be Π-the bonds. The increasing or due of inter nuclear distance is Cl – O < S – O < P – O < Si – 0
Therefore strength of pn—dΠ
bonding is Cl – O > S –O > P – O > Si – O
3.The decreasing order of dipole moment of molecules is
(a) NF3 > NH3 > H2O
(b) NH3 > NF3 > H2O
(c) H2O > NH3 > NF3
(d) H2O > NF3 > NH3
4.Which ones among CO32-, SO3, XeO3 and NO3– have planar structure?
(1) CO32–, SO3 and XeO3
(b) NO3–, SO3 and XeO3
(c) CO32- , NO3– and XeO3
(d) CO32- , SO3 and NO3–
sp2-hybridization sp2-hybridization sp3-hybridization Sp3-hybridization
(Trigonal planar) (Trigonal planar) (Trigonal pyramidal) (Trigonal pyramidal)
NO3–,CO32- and SO3have planar structure.
5.The correct schematic molecular energy diagram for SF6 molecule is
Consider SF6, which has six S-F bonds and hence 12 electrons involved in forming bonds and is therefore hypervalent. The simple basis set of atomic orbitals that are used to construct the molecular orbitals consists of the valence shell s and p orbitals of the S atom and one p orbital of each of the six F atoms and pointing towards the S atom. We use the F2p orbitals rather than the F2s orbitals because they match the S orbitals more closely in energy. From these ten atomic orbitals it is possible to construct ten molecular orbitals. Calculations indicate that four of the orbitals are bonding and four are antibonding; the two remaining orbitals are nonbonding.
(Reference : Inorganic Chemistry, Shriver Atkin)