View Slide Thumbnails		View Next Movie

3.3 MB, 52 seconds File: MOVIES/TRAM01/0060807.MOV

Voiceover
The methane model is a three-dimensional object. To show this three-dimensional structure on a flat piece of paper, a projection diagram is often used. Here, the shadow of the methane model is being sketched on a piece of paper. Bonds that are pointing out of the plane of the paper toward the viewer are shown with a wedged line. Bonds pointing behind the plane of the paper are represented by a dashed line.

Discussion
Two-dimensional drawings of methane such as those found in text books are shown. Structure 1 is a condensed formula, the structure 2 is a line bond representation that shown bonding but not geometry. Structure 3 is a projection drawing showing the spatial arrangement of the molecule. The derivation of this projection structure is shown.

Three-dimensional models of methane are shown below, first as a ball and stick model to emphasize bonding, then as a space filling model to emphasize electron density. Both models are shown side by side. The ball and stick model is placed inside a tetrahedron to show the geometry of the model.

Ball and Stick Model of Methane to Emphasize Bonding

Space Filling Model of Methane to Emphasize Electron Density.

Both Models Shown Side by Side

Ball and Stick Model of Methane and Tetrahedron

Ball and Stick Model of Methane inside Tetrahedron