(a) Define the term ‘isomers’. (b) Draw two possible isomers of the compound with molecular formula $C_3H_6O$ and write their names. (c) Give the electron dot structures of the above two compounds.

(a) Definition of Isomers

Isomers are compounds that have the same molecular formula but different structural arrangements of atoms, resulting in different physical and chemical properties. This phenomenon is known as isomerism.

(b) Two Isomers of $\text{C}_3\text{H}_6\text{O}$

The molecular formula $\text{C}_3\text{H}_6\text{O}$ corresponds to a saturated monohydric aldehyde or ketone. The two structural isomers are:

1. Propanone (a Ketone):

• Structural Formula:

$$\begin{array}{ccc} \text{H} & \text{O} & \text{H} \\ | & || & | \\ \text{H}-\text{C}- & \text{C} & -\text{C}-\text{H} \\ | & & | \\ \text{H} & & \text{H} \end{array}$$

1. Propanal (an Aldehyde):

• Structural Formula:

$$\begin{array}{ccc} \text{H} & \text{H} & \text{O} \\ | & | & || \\ \text{H}-\text{C}- & \text{C} & -\text{C}-\text{H} \\ | & | & \\ \text{H} & \text{H} & \end{array}$$

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(c) Electron Dot Structures

In these structures, dots ($\cdot$) and crosses ($\times$) represent the valence electrons shared between atoms to complete their octets/duplets.

#### 1. Electron Dot Structure of Propanone (Acetone)

$$\begin{array}{ccccccc} & \text{H} & & \bullet\bullet\ \text{O}\ \bullet\bullet & & \text{H} & \\ & \times\cdot & & \cdot\cdot\ \times\times & & \times\cdot & \\ \text{H}\ \times\cdot & \text{C} & \cdot\times & \text{C} & \times\cdot & \text{C} & \cdot\times\ \text{H} \\ & \times\cdot & & & & \times\cdot & \\ & \text{H} & & & & \text{H} & \end{array}$$

#### 2. Electron Dot Structure of Propanal (Propionaldehyde)

$$\begin{array}{ccccccc} & \text{H} & & \text{H} & & \bullet\bullet\ \text{O}\ \bullet\bullet & \\ & \times\cdot & & \times\cdot & & \cdot\cdot\ \times\times & \\ \text{H}\ \times\cdot & \text{C} & \cdot\times & \text{C} & \cdot\times & \text{C} & \times\cdot\ \text{H} \\ & \times\cdot & & \times\cdot & & & \\ & \text{H} & & \text{H} & & & \end{array}$$