From: poutnik@privacy.net   
      
   Dne 16/12/2017 v 04:54 Peter Fairbrother napsal(a):   
   > On 11/12/17 07:57, Alaia wrote:   
   >> On Sunday, 10 December 2017 02:08:41 UTC+8, John Smith  wrote:   
   >>> Is C2H2 planar molecule?Are linear moecules planar? Why?   
   >>   
   >> Is C3H4 a planar molecule? It's linear around the central C atom though.   
   >>   
   >   
   > C3H4 can refer to two molecules: H2C=C=CH2 propadiene (which is not   
   > linear, the planes of the pairs of hydrogen atoms at the ends are at   
   > right angles to each other) or propyne (not linear either, due to the 3D   
   > -CH3 group).   
   >   
   > Peter Fairbrother   
      
   They are definitely not planar, only C2H2 IS   
      
   But linear can be considered in 3 meanings   
      
     all atoms on the line -  only C2H2   
     all C atoms on the line. - all 3 ones   
     C chain without branches - all 3 ones   
      
   Generally, for the 2 former linear meanings   
   what is linear is planar, not necessarily vice versa.   
      
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   Poutnik ( The Pilgrim, Der Wanderer )   
      
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