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"An ionic bond is the force of attraction between oppositely charged ions in a compound."         This type of Chemical bond was proposed by Kossel (1916). Electrovalent bond is formed by transference of one or more electrons from the outermost shell of one atom to the valence shell of other. The atom losing electron becomes positive ion due to having more proton (having +ve charge) in the nucleus than electrons in shell. The atom which gains the electrons becomes –ve ion. Consequently, both the atoms acquire inert gas configuration.       Consider formation of NaCl from sodium and chlorine atoms. Sodium atom has one electron in the outermost shell, while Chlorine has seven electrons in its valence shell. When these two atoms come close each other, one electron from sodium is transferred to Chlorine atom.            The positive sodium ion Na + and the negative chloride ion Cl - ...

            The EAN rule is also called as the 18-electron rule of noble gas rule . According to this rule, the total number of electrons around the central metal ion including to those gained through co-ordination by the ligands is known as the effective atomic number of the central atom. In many cases this number is equal to the atomic number of next higher inert gas. EAN = Atomic no: of central atom ± Electron gained or lost + No. of electron denoted by ligands. Complex Atomic no: of central atom ± Electron gained or lost + No. of electron denoted by ligands. EAN [Ni(CO) 4 ] 28 - 0 + 2(4) 36 [Fe(CO) 5 ] 26 – 0 + 2(5) 36 [Fe(CN) 6 ] -4 26 - 2 + 2(6) 36 [Zn(NH 3 ) 4 ] 2+ 30 - 2 + 2(4) 36 [V(CO) 6 ] - 23 + 1 + 2(6) 36 [Pd(NH 3 ) 6 ] 4+ 78 – 4 + 2(6) 86 [Cr(NH 3 ) 6 ]...