Question

Draw chain and dot structure of first two alkanes

Answer 1

Hint:Here the dot structure refers to the Lewis structure and the chain structures refers to show the chemical bonding in the structure. From this much information it is easy to draw the following.

Complete answer:
First let us look into Lewis structure.
We know it is a simplified representation of valence shell electrons in a molecule. We are asked to draw the dot structure of the first two alkane. As we know the first two alkanes are methane $\left( {C{H_4}} \right)$ and ethane ${C_2}{H_6}$
Then the Lewis structure is obtained by drawing the valence electrons of carbons as dot around them. We know that carbon has four valence electrons. So, we can form 4 bonds with another atom since this is how they complete their octet of 8. When they share their electron with hydrogen which has one 1 electron, they have four electrons from hydrogens and the carbons complete their octet of 8. Also, hydrogen only needs 2 electrons in its shell therefore they also complete their shell. The shared electrons are presented in a circle.
Now for ethane the process is the same as we have two carbon atoms both of them have 3 hydrogen atoms to pair up with and the remaining one is shared among them the carbon atom to complete their octet.

Chain Structure:
In chain structure we represent the shared electrons in a line, as they are the covalent bond formed in between them. The concept for obtaining the octet is the same as the Lewis structure, the only difference is that we just draw a line in place of the circle.

Note:
When there are two electrons sharing the same atom we obtain double and if three atoms are shared with the same atom we obtain triples bonds. In chained structure they will have double lines and triple lines respectively.