i) What are F-centres in an ionic crystal?
(ii) Why are crystals having F-centres paramagnetic?
(i) Ionic compounds having non-stoichiometric defects, anionic vacancies are occupied by electrons. These are known as F-centres. These electrons are delocalised and responsible for importing colours to crystals.
(ii) Free impaired electrons occupying anionic vacancies spin in a particular direction result in the magnetic moment and ionic crystals with F-centres. So, they show paramagnetic behaviour.
For a crystal of diamond, state:
(i) The hybridisation of the carbon atom.
(ii) The coordination number of each carbon atom.
(iii) The type of lattice in which it crystalises.
(iv) The number of carbon atoms present per unit cell.
Write the formulae of the following coordination compounds:
(i) potassiumtetracyanonickel(II)
(ii) triamminetrinitrocobalt(III)
[CoF6]3- is a coordination complex ion.
(i) What is the oxidation number of cobalt in the complex?
(ii) How many unpaired electrons are there in the complex?
(iii) State the magnetic behaviour of the complex.
(iv) Give the I.U.P.A.C. name of the complex.