Worksheet starter|KS3 Chemistry - Free Printable

Let's solve the task step by step.

We are given a table with the name of substance, a diagram of the molecule, and we need to fill in the chemical formula and determine whether it is an element or compound.

---

🔍 Definitions:

- Element: A substance made of only one type of atom.
- Compound: A substance made of two or more different types of atoms chemically bonded together.

---

Now, let’s go through each row:

---

1. Water

- Diagram: One oxygen (O) atom bonded to two hydrogen (H) atoms.
- Chemical formula: H₂O
- Element or compound?: Compound (two different elements: H and O)

✔ Answer:
- Chemical formula: H₂O
- Element or compound? Compound

---

2. Nitrogen

- Diagram: Two nitrogen (N) atoms bonded together.
- Chemical formula: N₂
- Element or compound?: Element (only nitrogen atoms)

✔ Answer:
- Chemical formula: N₂
- Element or compound? Element

---

3. Carbon dioxide

- Diagram: One carbon (C) atom bonded to two oxygen (O) atoms.
- Chemical formula: CO₂
- Element or compound?: Compound (C and O)

✔ Answer:
- Chemical formula: CO₂
- Element or compound? Compound

---

4. Ammonia

- Diagram: One nitrogen (N) atom bonded to three hydrogen (H) atoms.
- Chemical formula: NH₃
- Element or compound?: Compound (N and H)

✔ Answer:
- Chemical formula: NH₃
- Element or compound? Compound

---

5. Sulfur dioxide

- Diagram: One sulfur (S) atom bonded to two oxygen (O) atoms.
- Chemical formula: SO₂
- Element or compound?: Compound (S and O)

✔ Answer:
- Chemical formula: SO₂
- Element or compound? Compound

---

6. Hydrogen

- Diagram: Two hydrogen (H) atoms bonded together.
- Chemical formula: H₂
- Element or compound?: Element (only hydrogen atoms)

✔ Answer:
- Chemical formula: H₂
- Element or compound? Element

---

7. Hydrogen chloride

- Diagram: One hydrogen (H) atom bonded to one chlorine (Cl) atom.
- Chemical formula: HCl
- Element or compound?: Compound (H and Cl)

✔ Answer:
- Chemical formula: HCl
- Element or compound? Compound

---

8. Oxygen

- Diagram: Two oxygen (O) atoms bonded together.
- Chemical formula: O₂
- Element or compound?: Element (only oxygen atoms)

✔ Answer:
- Chemical formula: O₂
- Element or compound? Element

---

✔ Final Completed Table:

| Name of substance | Diagram of molecule | Chemical formula | Element or compound? |
|-------------------|---------------------|------------------|------------------------|
| Water | H–O–H | H₂O | Compound |
| Nitrogen | N≡N | N₂ | Element |
| Carbon dioxide | O=C=O | CO₂ | Compound |
| Ammonia | H₃N (trigonal pyramidal) | NH₃ | Compound |
| Sulfur dioxide | O=S=O | SO₂ | Compound |
| Hydrogen | H–H | H₂ | Element |
| Hydrogen chloride | H–Cl | HCl | Compound |
| Oxygen | O=O | O₂ | Element |

> Note: The diagrams show molecular structures, and the formulas reflect how many atoms of each element are present.

---

📝 Summary:

- Elements (same type of atoms): Nitrogen (N₂), Hydrogen (H₂), Oxygen (O₂)
- Compounds (different types of atoms): Water (H₂O), Carbon dioxide (CO₂), Ammonia (NH₃), Sulfur dioxide (SO₂), Hydrogen chloride (HCl)

Let me know if you'd like this as a downloadable table!