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Werner's Theory
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Explains the fundamental postulates of werner's theory, representation of co-ordination compounds and calculating the number of ions formed

Budumuru Pushpalatha
M.Sc.,B.Ed., SET qualified; 11+ years of teaching experience, Reading books, listening music, Gardening

Unacademy user
well explained mam,mam education subject m symbolic interaction new add hua h, plz uske upper video lae or sath m question taki samaj ske topic exam m kase aayega, plz jaldii lae, exam aa hi gya
Sakshi Patel
5 months ago
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  2. About Me M.Sc; B.Ed 3 Years of Industrial Experience 11+ Years of Teaching Experience Reading Books, Listening Music,Gardening Rate Review Recommend and Share

  3. WERNER,S THEORY Metals possess two types of valencies Primary / principal / ionizable valency Secondary / auxillary / non-ionizable valency Primary valency corresponds to oxidation number For example, in the formation of PtCl4 the primary valency of Pt is 4 Primary Valency is satisfied by negative ions

  4. Secondary valency corresponds to coordination number Secondary valencies are satisfied by negative ions, neutral molecules or even some positive groups. Primary valencies are shown by dotted lines and secondary valencies are shown by thick lines. primary valencie.. secondary valencies

  5. Primary Valencies are Non-Directional where as secondary Valencies are Directional To distinguish between the two types of Valencies, werner introduced the square brackets[] The portion enclosed in the bracket is coordination sphere and the portion present out side the bracket as ionising sphere

  6. Thus according to Werner theory, the compound CoCl 6NH3 written as [Co(NHC. Six ammonia molecules satisfy the six secondary valencies of cobalt. They are directly attached to the cot So they are shown by thick lines. 9 The oxidation state of cobalt is +3, d cNH2 satisfied by three chloride ions These are shown by dotted lines. H2 It can be represented as here:

  7. The three chloride ions present in ionising sphere are loosely bound Therefore the total number of ions 1+3 4 Let us take another complex of coCl3 with NHais COCl3.5NH, To satisfy the six secondary valencies of cobalt, one chloride ion must be present inside the coordination sphere.

  8. Thus the six secondary valencies (5 by ammonia and one satisfied by CI) are shown by thick lines The three primary valencies of cobalt are satisfied by three chloride ions, these are shown by dotted lines Here one chloride ion assumes a Dual behaviour. Hence such chloride ion is shown d by both thick and dotted lines irn the structure Nia NH3

  9. Thus the complex COC.5NH2 will ionise in solution as below 3* On ionisation it forms 3 ions .Similarly, the compound COCI2.4NH formulated as 3* [Co(NH)Cl,]Cl and on ionisation forms two ions

  10. Applications: It predicts the exact structure of each complex. .It explains why a particular metal and particular ligand form different complexes. It also explains the different properties of each complex It predicts the structure of different complexes with coordination number 4 and 6 .

  11. Thank you for watching