This set consists of sufficient parts to make models of benzene, ethane, ethene and ethyne. The atom cores are represented by the standard Molymod® atom parts, and the atomic and molecular orbital parts by colour-coded, matt or pastel-coloured pieces. These exclusively designed models help to demonstrate both sigma-bonding and pi-bonding and therefore the concept of electron delocalisation and orbital hybridisation. Atoms:. 2 x carbon (6 holes). 8 x carbon (5 holes). 2 x carbon (4 holes). 18 x hydrogen (1 hole). Bonds:. 9 x carbon-carbon (oval shaped) sigma-bonds. 18 x carbon-hydrogen (pear shaped) sigma-bonds. 9 x pi-bonds (21 pink and 21 purple pieces).