For 1,2-dichloroethane:(a) Draw Newman projections for all eclipsed conformations formed

Key concepts

Strain

Strain is a measure of the energy stored in a compound due to a structural distortion. It is an  instability within a structure associated with higher internal energy.

Newman projection

A way to view a molecule by looking along a carbon-carbon single bond to help evaluate the relative orientations of attached groups.

Conformation

Any three-dimensional arrangement of atoms in a molecule that results from rotation about a single bond.

Staggered conformation

A conformation about a carbon-carbon single bond in which the atoms or groups on one carbon are as far apart as possible from atoms or groups on an adjacent carbon.

Eclipsed conformation

A conformation about a carbon-carbon single bond in which the atoms or groups on one carbon are as close as possible to the atoms or groups on an adjacent carbon.

Dihedral angle

The angle created by two intersecting planes.

Anti conformation 

A conformation about a single bond in which two groups on adjacent carbons lie at a dihedral angle of 180°.

Gauche conformation

A conformation about a single bond of an alkane in which two groups on adjacent carbons lie at a dihedral angle of 60°.

Steric strain

The strain that arises when nonbonded atoms separated by four or more bonds are forced closer to each other than their atomic (contact) radii would allow. Steric strain is also called nonbonded interaction strain or van der Waals strain.

Step 1 of 4

The molecule given is  1,2-dichloroethane,

First we are asked to draw the Newman projection and to answer the sub questions.

Newman projection  is a way to view a molecule by looking along a carbon-carbon single bond to help evaluate the relative orientations of attached groups.

So first we can draw the simple lewis structure of the molecule