Fill in the missing spaces in the table of chemical formulae, including substance names, molecular diagrams, chemical formulas, and element or compound classification.

I'll work through this table systematically, filling in the chemical formulas and determining whether each substance is an element or compound.

Let me analyze each row:

1. Water
- Diagram shows: 2 hydrogen atoms (H) + 1 oxygen atom (O)
- Chemical formula: H₂O
- Contains different types of atoms (H and O), so it's a compound

2. Nitrogen
- Diagram shows: 2 nitrogen atoms (N) bonded together
- Chemical formula: N₂
- Contains only one type of atom (N), so it's an element

3. Carbon dioxide
- Diagram shows: 1 carbon atom (C) + 2 oxygen atoms (O)
- Chemical formula: CO₂
- Contains different types of atoms (C and O), so it's a compound

4. Ammonia
- Diagram shows: 1 nitrogen atom (N) + 3 hydrogen atoms (H)
- Chemical formula: NH₃
- Contains different types of atoms (N and H), so it's a compound

5. Sulfur dioxide
- Diagram shows: 1 sulfur atom (S) + 2 oxygen atoms (O)
- Chemical formula: SO₂
- Contains different types of atoms (S and O), so it's a compound

6. Hydrogen
- Diagram shows: 2 hydrogen atoms (H) bonded together
- Chemical formula: H₂
- Contains only one type of atom (H), so it's an element

7. Hydrogen chloride
- Diagram shows: 1 chlorine atom (Cl) + 1 hydrogen atom (H)
- Chemical formula: HCl
- Contains different types of atoms (H and Cl), so it's a compound

8. Oxygen
- Diagram shows: 2 oxygen atoms (O) bonded together
- Chemical formula: O₂
- Contains only one type of atom (O), so it's an element

Key concept to remember:
- An element contains only one type of atom (even if there are multiple atoms bonded together like O₂ or N₂)
- A compound contains two or more different types of atoms chemically bonded together

Final Answer:

| Name of substance | Chemical formula | Element or compound? |
|-------------------|------------------|---------------------|
| Water | H₂O | Compound |
| Nitrogen | N₂ | Element |
| Carbon dioxide | CO₂ | Compound |
| Ammonia | NH₃ | Compound |
| Sulfur dioxide | SO₂ | Compound |
| Hydrogen | H₂ | Element |
| Hydrogen chloride | HCl | Compound |
| Oxygen | O₂ | Element |