From: patrizio.pan-2002@libero.it   
      
   On Saturday, December 16, 2017 at 4:54:09 AM UTC+1, Peter Fairbrother wrote:   
   > 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).   
      
   There is also cyclopropene, the least stable of the three regular isomers.   
   What is planar here is the carbon's ring and two of the four hydrogens,   
   the others are in a perpendicular plane.   
      
   > Peter Fairbrother   
      
   regards   
   Angelo   
      
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