Question

(a) Give the postulates of valence bond theory of coordination compounds.
(b) Differentiate chemical reactions from nuclear reactions.

Answer 1

Coordination compounds contain a central metal atom along with ligands attached. The formation of coordination compounds depends on valence bond theory of coordination compounds. Nuclear reactions involve radioactive substances to carry on the nuclear fusion or fission.

Complete step-by-step answer:(a) Postulates are the rules on which any theory is based. Postulates for valence bond theory for coordination compounds are:
-metal atoms which are under the influence of ligands, use its s, p, d, and f orbitals for hybridization in forming hybrid orbitals.
- the number of vacant orbits available in the central metal atom decides its coordination number.
- the hybrid orbitals overlap with ligand orbitals and ligand give the electrons to the metal orbital, thus bonding happens.
- ligands are arranged around the metal in a way that makes the geometry of the complex. The geometry may be tetrahedral$(s{{p}^{3}})$ , octahedral $({{d}^{2}}s{{p}^{3}}\,,\,s{{p}^{3}}{{d}^{2}})$, or square planar$(ds{{p}^{2}})$.
- weak ligands are not able to pair the electrons of the metal, they are, $C{{l}^{-}},B{{r}^{-}},{{I}^{-}}$etc.
- strong ligands are able to pair the electrons of the central metal, they are $C{{N}^{-}}$, en, CO etc.
Hence, the postulates of valence bond theory of coordination compounds are mentioned.
(b) the difference between chemical and nuclear reactions are:
-Chemical reactions deal with the loss or gain or sharing of electrons in the products formed, while nuclear reactions have the emission of alpha, beta and gamma particles in the reaction taking place.
- chemical reactions are balanced for the mass values, while the nuclear reactions are balanced for the values of mass as well as energy.
- low amounts of energy are released in any chemical reaction, while a very high amount of energy is released in a nuclear reaction.
- the unit of energy for a chemical reaction is kiloJoule per mole, while for a nuclear reaction it is MeV, million electron volts.
- The nucleus of an atom is not affected in a chemical reaction, so no new element is formed, while the nucleus is involved in the nuclear reaction that forms a new element, usually isotopes.
Hence, the difference between chemical and nuclear reactions are discussed.

Note: Coordination compounds possess some magnetic moment due to the unpaired electrons which is calculated as spin only magnetic moment, ${{\mu }_{s}}=\sqrt{n(n+2)BM}$, where BM is bohr magneton. Nuclear reactions are used in making nuclear weapons.