Functional Group ID Worksheet - Free Printable

Let's go through each of the 15 organic compounds in the worksheet and identify, circle, and name the functional groups present. I'll explain each one step by step.

---

Functional Group Identification

#### 1.
```
H O H
| | |
H-C-C-C-H
| |
H H
```
- Structure: A three-carbon chain with an oxygen atom between the middle and end carbon.
- The central carbon is bonded to two carbons and one oxygen (–O–), and the terminal carbon has an OH group.
- This is ethanol, but wait — let’s look closely:
- It's H₃C–CH(OH)–CH₃, which is 2-propanol.
- Functional group: Hydroxyl (–OH) → Alcohol
- ✔ Circle the –OH group
- Name: Alcohol

---

#### 2.
```
H H
| |
H-C-C-N-H
| |
H H
```
- Nitrogen attached to a carbon and two hydrogens.
- This is a methylamine: CH₃–CH₂–NH₂
- Functional group: Amino group (–NH₂) → Amine
- ✔ Circle the –NH₂ group
- Name: Amine

---

#### 3.
```
H O
| ||
H-C-C-O-H
|
H
```
- Central carbon double-bonded to O and single-bonded to OH → Carboxylic acid
- Structure: CH₃COOH → Acetic acid
- ✔ Circle the –COOH group (the C=O and –OH together)
- Name: Carboxylic acid

---

#### 4.
```
H H
| |
H-C-C-O-H
| |
H H
```
- Terminal carbon with –OH group → CH₃CH₂OH → Ethanol
- Functional group: Hydroxyl (–OH) → Alcohol
- ✔ Circle the –OH group
- Name: Alcohol

---

#### 5.
```
H
|
C=O
|
H
```
- Carbon double-bonded to oxygen, with two H atoms → Formaldehyde (H₂C=O)
- Functional group: Carbonyl (C=O) with two H atoms → Aldehyde
- ✔ Circle the C=O group
- Name: Aldehyde

---

#### 6.
```
O
||
H-C-H
```
- Same as #5: H₂C=O → Formaldehyde
- ✔ Circle the C=O group
- Name: Aldehyde

---

#### 7.
```
O
║
/ \
/ \
/ \
/ \
```
- Cyclohexanone: six-membered ring with a C=O group
- Functional group: Carbonyl (C=O) inside a ring → Ketone
- ✔ Circle the C=O group
- Name: Ketone

---

#### 8.
```
H S H
| | |
H-C-C-C-H
| | |
H H H
```
- Carbon bonded to sulfur (S) → Thiol group (–SH) → Thiol
- Structure: CH₃CH₂SH → Ethane thiol
- ✔ Circle the –SH group
- Name: Thiol

---

#### 9.
```
H N O
| | ||
H-C-C-O-H
| | |
H H H
```
- Nitrogen attached to carbon and two H → amine
- Also has –COOH → carboxylic acid
- So it has two functional groups:
- –NH₂: Amine
- –COOH: Carboxylic acid
- This is amino acid (like glycine)
- ✔ Circle both –NH₂ and –COOH groups
- Names: Amine and Carboxylic acid

---

#### 10.
```
H O H
| | |
H-C-C-C-S-H
| | |
H H H
```
- Terminal –SH group → Thiol
- Also has –OH on middle carbon → Alcohol
- So two functional groups:
- –OH: Alcohol
- –SH: Thiol
- ✔ Circle both –OH and –SH groups
- Names: Alcohol and Thiol

---

#### 11.
```
H H O
| | ||
H-C-C-C-H
| | |
H H H
```
- Terminal carbonyl (C=O) → Aldehyde
- Structure: CH₃CH₂CHO → Propanal
- ✔ Circle the C=O group at the end
- Name: Aldehyde

---

#### 12.
```
O
║
/ \
/ \
/ \
```
- Five-membered ring with a –COOH group attached → cyclopentanecarboxylic acid
- Functional group: –COOH → Carboxylic acid
- ✔ Circle the –COOH group
- Name: Carboxylic acid

---

#### 13.
```
O
║
/ \
/ \
/ \
```
- Five-membered ring with –CHO group → cyclopentanal
- Functional group: Aldehyde (C=O at end of side chain)
- ✔ Circle the C=O group
- Name: Aldehyde

---

#### 14.
```
H
|
H-C-O-H
| |
H-C-C-N-H
| | |
H H H
```
- Let's analyze:
- Central carbon bonded to –OH → Alcohol
- Also bonded to nitrogen → Amine
- Structure: CH₃CH(OH)CH₂NH₂ → 1-amino-2-propanol
- Functional groups:
- –OH: Alcohol
- –NH₂: Amine
- ✔ Circle both –OH and –NH₂ groups
- Names: Alcohol and Amine

---

#### 15.
```
O-H
|
/ \
/ \
/ \
```
- Cyclohexane ring with –OH group → Cyclohexanol
- Functional group: Hydroxyl (–OH) → Alcohol
- ✔ Circle the –OH group
- Name: Alcohol

---

✔ Final Answers Summary:

| Number | Compound | Functional Group(s) | Name(s) |
|--------|---------|----------------------|---------|
| 1 | CH₃CH(OH)CH₃ | –OH | Alcohol |
| 2 | CH₃CH₂NH₂ | –NH₂ | Amine |
| 3 | CH₃COOH | –COOH | Carboxylic acid |
| 4 | CH₃CH₂OH | –OH | Alcohol |
| 5 | H₂C=O | C=O | Aldehyde |
| 6 | H₂C=O | C=O | Aldehyde |
| 7 | Cyclohexanone | C=O (ketone) | Ketone |
| 8 | CH₃CH₂SH | –SH | Thiol |
| 9 | H₂N–CH₂–COOH | –NH₂, –COOH | Amine, Carboxylic acid |
| 10 | HO–CH₂–CH₂–SH | –OH, –SH | Alcohol, Thiol |
| 11 | CH₃CH₂CHO | C=O (aldehyde) | Aldehyde |
| 12 | Cyclopentane–COOH | –COOH | Carboxylic acid |
| 13 | Cyclopentane–CHO | C=O (aldehyde) | Aldehyde |
| 14 | CH₃CH(OH)CH₂NH₂ | –OH, –NH₂ | Alcohol, Amine |
| 15 | Cyclohexanol | –OH | Alcohol |

---

🔍 How to Circle:

For each molecule, circle the key part of the functional group:
- Alcohol: Circle the –OH group
- Amine: Circle the –NH₂ or nitrogen with its bonds
- Carboxylic acid: Circle the –COOH group (C=O and –OH together)
- Aldehyde: Circle the C=O at the end of the chain
- Ketone: Circle the C=O in the middle of a chain or ring
- Thiol: Circle the –SH group
- Etc.

---

✔ Answer Key for Worksheet:

1. Alcohol
2. Amine
3. Carboxylic acid
4. Alcohol
5. Aldehyde
6. Aldehyde
7. Ketone
8. Thiol
9. Amine and Carboxylic acid
10. Alcohol and Thiol
11. Aldehyde
12. Carboxylic acid
13. Aldehyde
14. Alcohol and Amine
15. Alcohol

Let me know if you'd like a visual version or printable answer sheet!