Draw the structural formula of ethane. Draw electron-dot structure of propane.

To understand the structural formulas of ethane and propane, let’s break down each compound step by step. Ethane (C2H6) is a simple alkane, while propane (C3H8) is slightly more complex. Both are hydrocarbons, meaning they consist solely of carbon and hydrogen atoms.

Ethane: Structural Formula

The structural formula of ethane can be represented as follows:

• Each carbon atom is bonded to three hydrogen atoms.
• The two carbon atoms are connected by a single bond.

Visually, you can depict ethane like this:

H₃C—C H₃

This shows that each carbon (C) atom is surrounded by hydrogen (H) atoms, forming a stable molecule. The single bond between the two carbon atoms indicates that they share two electrons, one from each carbon.

Propane: Electron-Dot Structure

Now, let’s move on to propane. The electron-dot structure, also known as the Lewis structure, illustrates the valence electrons of the atoms involved. For propane (C3H8), here’s how you can visualize it:

• Each carbon atom has four valence electrons.
• Each hydrogen atom has one valence electron.

The electron-dot structure for propane can be drawn as follows:

H H H
| | |
H—C—C—C—H
| | |
H H H

In this representation, each line (—) indicates a pair of shared electrons (a bond). Each carbon atom is bonded to two other carbon atoms and enough hydrogen atoms to satisfy the tetravalency of carbon, meaning each carbon atom forms four bonds in total.

Understanding the Bonding

Both ethane and propane are examples of saturated hydrocarbons, meaning they contain only single bonds between carbon atoms. This saturation is important because it affects the chemical reactivity and physical properties of these compounds.

In summary, ethane consists of two carbon atoms connected by a single bond, each bonded to three hydrogen atoms, while propane has three carbon atoms in a chain, each bonded to enough hydrogen atoms to fulfill carbon's bonding requirements. Understanding these structures helps in grasping the fundamentals of organic chemistry and the behavior of hydrocarbons.