Write the structure of 3-pentanone.

Answer

To write the structure of 3-pentanone, we can follow these steps:

### Step 1: Identify the root name and the number of carbon atoms
The root name "pent" indicates that the compound has 5 carbon atoms.

### Step 2: Determine the functional group
The suffix "one" indicates that the compound is a ketone, which means it has a carbonyl group (C=O) present.

### Step 3: Locate the position of the functional group
The number "3" in 3-pentanone tells us that the carbonyl group is located on the third carbon atom of the chain.

### Step 4: Draw the carbon chain
We start by drawing a straight chain of 5 carbon atoms:
```
C1 - C2 - C3 - C4 - C5
```

### Step 5: Add the carbonyl group
Since the carbonyl group is on the third carbon, we replace one of the bonds on C3 with a double bond to oxygen (C=O):
```
C1 - C2 - C3(=O) - C4 - C5
```

### Step 6: Satisfy the valency of carbon atoms
Each carbon atom has a valency of 4. We need to add hydrogen atoms to satisfy this valency:
- C1 (CH3)
- C2 (CH2)
- C3 (C=O, no H)
- C4 (CH2)
- C5 (CH3)

### Final Structure
The complete structure of 3-pentanone can be represented as:
```
O
||
CH3-CH2-C-CH2-CH3
```

### Summary of the Structure
The structure of 3-pentanone is:
```
O
||
CH3-CH2-C-CH2-CH3
```