Chemistry worksheet for practicing naming and writing formulas of covalent compounds.

Let's solve this step-by-step. This worksheet is about naming covalent (molecular) compounds and writing their chemical formulas. Covalent compounds are formed between two nonmetals, and we use prefixes to indicate the number of atoms.

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🔷 Rules for Naming Covalent Compounds:

1. The first element is named using its full name.
2. The second element is named with an "-ide" ending.
3. Prefixes (mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-) are used to indicate the number of atoms.
4. "Mono-" is usually omitted for the first element but always used for the second element if there’s only one.
5. The prefix "mono-" is not used for the first element.

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## ✔ Part A: Name the Covalent Compounds

| Formula | Name |
|--------|------|
| 1. CO | Carbon monoxide |
| 2. CO₂ | Carbon dioxide |
| 3. N₂O₃ | Dinitrogen trioxide |
| 4. NP | Nitrogen monophosphide *(Note: This is unusual; typically not common, but by rules it would be)* |
| 5. SCl₂ | Sulfur dichloride |
| 6. P₂O₅ | Diphosphorus pentoxide |
| 7. NBr₃ | Nitrogen tribromide |
| 8. Cl₄ | Tetraclorine *(But this is not a standard compound — likely meant to be CCl₄ or something else. However, if it's just Cl₄, it's called *tetrachlorine*, though it's not stable. But in naming, it would be tetrachlorine*) |
| 9. CCl₄ | Carbon tetrachloride |
| 10. PF₅ | Phosphorus pentafluoride |
| 11. SeF₂ | Selenium difluoride |
| 12. TeBr₂ | Tellurium dibromide |
| 13. P₂S₅ | Diphosphorus pentasulfide |
| 14. C₃N₄ | Tricarbon tetranitride |
| 15. CH₄ | Methane *(Common name, but technically it's carbon tetrahydride, but methane is accepted)* |
| 16. PH₃ | Phosphorus trihydride *(or phosphine, but the systematic name is phosphorus trihydride)* |

> ⚠️ Note: For some compounds like CH₄ and PH₃, common names are widely used, but in systematic naming, we can use prefixes.

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## ✔ Part B: Write the Chemical Formula

Use prefixes to determine subscripts:

| Name | Formula |
|------|---------|
| 1. carbon tetrafluoride | CF₄ |
| 2. silicon dioxide | SiO₂ |
| 3. dinitrogen trisulfide | N₂S₃ |
| 4. phosphorus mononitride | PN *(This is rare; might not be stable, but formula is PN)* |
| 5. carbon disulfide | CS₂ |
| 6. dinitrogen trichloride | N₂Cl₃ |
| 7. silicon tetrabromide | SiBr₄ |
| 8. carbon dioxide | CO₂ |
| 9. nitrogen trifluoride | NF₃ |
| 10. boron trisulfide | B₂S₃ *(Wait — “boron trisulfide” suggests one B and three S → BS₃? But actual formula is B₂S₃. So correct interpretation: "trisulfide" means 3 sulfurs, but boron forms B₂S₃. So need to balance.)<br>Actually, boron trisulfide = B₂S₃ (because boron has +3 oxidation state, sulfur -2). So it's B₂S₃. |
| 11. disulfur trioxide | S₂O₃ |
| 12. selenium tetrafluoride | SeF₄ |
| 13. diphosphorus pentasulfide | P₂S₅ |
| 14. sulfur dibromide | SBr₂ |
| 15. carbon tetrachloride | CCl₄ |
| 16. dinitrogen tetroxide | N₂O₄ |

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✔ Final Answers:

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Part A: Names

1. CO → Carbon monoxide
2. CO₂ → Carbon dioxide
3. N₂O₃ → Dinitrogen trioxide
4. NP → Nitrogen monophosphide
5. SCl₂ → Sulfur dichloride
6. P₂O₅ → Diphosphorus pentoxide
7. NBr₃ → Nitrogen tribromide
8. Cl₄ → Tetrachlorine *(rare, but possible)*
9. CCl₄ → Carbon tetrachloride
10. PF₅ → Phosphorus pentafluoride
11. SeF₂ → Selenium difluoride
12. TeBr₂ → Tellurium dibromide
13. P₂S₅ → Diphosphorus pentasulfide
14. C₃N₄ → Tricarbon tetranitride
15. CH₄ → Methane *(or carbon tetrahydride)*
16. PH₃ → Phosphorus trihydride *(or phosphine)*

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Part B: Formulas

1. carbon tetrafluoride → CF₄
2. silicon dioxide → SiO₂
3. dinitrogen trisulfide → N₂S₃
4. phosphorus mononitride → PN
5. carbon disulfide → CS₂
6. dinitrogen trichloride → N₂Cl₃
7. silicon tetrabromide → SiBr₄
8. carbon dioxide → CO₂
9. nitrogen trifluoride → NF₃
10. boron trisulfide → B₂S₃
11. disulfur trioxide → S₂O₃
12. selenium tetrafluoride → SeF₄
13. diphosphorus pentasulfide → P₂S₅
14. sulfur dibromide → SBr₂
15. carbon tetrachloride → CCl₄
16. dinitrogen tetroxide → N₂O₄

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✔ Summary:
- Use prefixes to determine atom counts.
- First element: no "mono-" unless needed (but never for first).
- Second element: always uses "-ide" and includes "mono-" if only one atom.
- Balance charges only if ions involved — but here all are covalent, so just follow prefixes.

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