Question

In which conformation the hydrogen
atoms of the two carbon atoms are
oriented in such away so, that they lie
for a part from one another

Answer 1

Answer:

Most organic molecules, including all alkanes, are not planar but are instead characterized by three-dimensional structures. Methane, for example, has the shape of a regular tetrahedron with carbon at the centre and a hydrogen atom at each corner. Each H―C―H angle in methane is 109.5°, and each C―H bond distance is 1.09 angstroms (Å; 1Å = 1 × 10−10 metre). Higher alkanes such as butane have bonds that are tetrahedrally disposed on each carbon except that the resulting C―C―C and H―C―H angles are slightly larger and smaller, respectively, than the ideal value of 109.5° characteristic of a perfectly symmetrical tetrahedron. Carbon-carbon bond distances in alkanes are normally close to 1.53 angstroms.

chemical structure of methane

chemical structure of methane

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.)

Encyclopædia Britannica, Inc.

Explanation:

An important aspect of the three-dimensional shape of alkanes and other organic molecules is their conformations, the nonidentical arrangements of atoms that are generated by rotation about single bonds. Of the infinite number of conformations possible for ethane—which are related by tiny increments of rotation of one CH3 group with respect to the other—the eclipsed conformation is the least stable, and the staggered conformation is the most stable. The eclipsed conformation is said to suffer torsional strain because of repulsive forces between electron pairs in the C―H bonds of adjacent carbons. These repulsive forces are minimized in the staggered conformation since all C―H bonds are as far from one another as possible. Although rotation about the C―C bond of ethane is exceedingly rapid (millions of times per second at room temperature), at any instant most of the molecules exist in the staggered conformation.