Propane three-dimensional model

Three-dimensional models of ethane, propane, and butane. The ball-and-stick models at the left show the way in which the atoms are connected and depict the correct bond angles. The spacefilling models at the right are constructed to scale and give a better idea of the molecular shape, though some of the hydrogens may appear hidden. 

A Figure 25.5 Three-dimensional models for propane (CsHg), showing rotations about the carbon-carbon single bonds. 

Lewis structure and ball-and-stick models of ethane (a) and propane (b). All the carbon atoms have tetrahedral shapes, because each has four pairs of electrons to separate in three-dimensional space. 

The three-dimensional representations and the ball-and-stick models for these alkanes indicate the tetrahedral geometry around each carbon atom. In contrast, the Lewis structures are not meant to imply any three-dimensional arrangement. Moreover, in propane and higher molecular weight alkanes, the carbon skeleton can be drawn in a variety of different ways and still represent the same molecule. 

Figure 27-4 Ball-and-stick and space-filling models and a three-dimensional representation of propane, C3Hg.

FIGURE 2.4 Space-filling models of (a) pentane, (b) 2-methylbutane, and (c) 2,2-dlmethyl-propane. The most branched Isomer, 2,2-dlmethylpropane, has the most compact, most spherical, three-dimensional shape. 

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