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How does a Newman projection show the structure of ethane?

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Two diagrams show the three-dimensional structure of a methane molecule: panel A uses a ball-and-stick model with a central carbon atom connected to four hydrogen atoms in a tetrahedral arrangement, while panel B illustrates the bond angle of 109.5 degrees and bond length of 1.09 angstroms between carbon and hydrogen atoms. — isomerism Tetrahedral geometry of methane: (A) stick-and-ball model and (B) diagram showing bond angles and distances. (Plain bonds represent bonds in the plane of the image; wedge and dashed bonds represent those directed toward and away from the viewer, respectively.)

A Newman projection is a specialized tool used in chemistry to visualize the spatial arrangement of atoms in a molecule by sighting directly down a specific bond—in the case of ethane, the carbon-carbon bond.12

In this projection:
* The front carbon is represented as the intersection point of the three bonds connecting it to its attached hydrogen atoms.12
* The back carbon is depicted as an exploded circle, with its three attached hydrogen bonds emanating outward from the circle's circumference.12

This visualization is particularly useful for distinguishing between two limiting conformational structures:
* Staggered ethane: The carbon-hydrogen bonds on the front and back carbons are positioned as far apart as possible.12
* Eclipsed ethane: The carbon-hydrogen bonds are aligned as closely as possible, creating torsional strain due to electron repulsion between the bonds.12

By using a Newman projection, chemists can clearly observe these orientations and analyze the energy differences between different rotational states of the molecule.12