You're absolutely right to focus on the key rule shown in your image:
>
Metal + Nonmetal = Ionic Bonding
>
Nonmetal + Nonmetal = Covalent Bonding
This is a reliable and simple guideline for predicting bond type in many common compounds — especially for introductory chemistry.
Let’s go through each compound one by one, applying this rule.
---
1. H₂ (Hydrogen gas)
- Both atoms are
hydrogen, which is a
nonmetal.
-
Nonmetal + Nonmetal → Covalent
✔ Answer: Covalent
---
2. Cl₂ (Chlorine gas)
- Both atoms are
chlorine, a
nonmetal.
-
Nonmetal + Nonmetal → Covalent
✔ Answer: Covalent
---
3. O₂ (Oxygen gas)
- Both atoms are
oxygen, a
nonmetal.
-
Nonmetal + Nonmetal → Covalent
✔ Answer: Covalent
---
4. HCl (Hydrogen chloride)
- Hydrogen (H) is a
nonmetal.
- Chlorine (Cl) is a
nonmetal.
-
Nonmetal + Nonmetal → Covalent
⚠️ *Note: Although HCl can ionize in water (forming H⁺ and Cl⁻), as a pure molecule it is covalently bonded. In solid/liquid/gas state without water, it’s covalent.*
✔ Answer: Covalent
---
5. LiF (Lithium fluoride)
- Lithium (Li) is a
metal (alkali metal).
- Fluorine (F) is a
nonmetal (halogen).
-
Metal + Nonmetal → Ionic
✔ Answer: Ionic
---
6. NaCl (Sodium chloride)
- Sodium (Na) is a
metal.
- Chlorine (Cl) is a
nonmetal.
-
Metal + Nonmetal → Ionic
✔ Answer: Ionic
---
7. NaF (Sodium fluoride)
- Sodium (Na) is a
metal.
- Fluorine (F) is a
nonmetal.
-
Metal + Nonmetal → Ionic
✔ Answer: Ionic
---
8. MgF (Magnesium fluoride — note: correct formula is MgF₂, but we’ll use as given)
- Magnesium (Mg) is a
metal.
- Fluorine (F) is a
nonmetal.
-
Metal + Nonmetal → Ionic
✔ Answer: Ionic
*(Even though the formula should be MgF₂ for charge balance, the bonding type remains ionic.)*
---
9. NH₃ (Ammonia)
- Nitrogen (N) is a
nonmetal.
- Hydrogen (H) is a
nonmetal.
-
Nonmetal + Nonmetal → Covalent
✔ Answer: Covalent
---
##
✔ Final Answer Table:
| Molecule | Formula | Ionic or Covalent? |
|--------------|---------|---------------------|
| Hydrogen | H₂ |
Covalent |
| Chlorine | Cl₂ |
Covalent |
| Oxygen | O₂ |
Covalent |
| Hydrogen Chloride | HCl |
Covalent |
| Lithium Fluoride | LiF |
Ionic |
| Sodium Chloride | NaCl |
Ionic |
| Sodium Fluoride | NaF |
Ionic |
| Magnesium Fluoride | MgF |
Ionic |
| Ammonia | NH₃ |
Covalent |
---
## 💡 Extra Tip:
Sometimes students get confused with
HCl and
NH₃ because they dissolve in water to form ions — but
in their pure molecular form, they are held together by
covalent bonds. The rule “Metal + Nonmetal = Ionic” still holds perfectly here.
Let me know if you’d like to dive deeper into why ionic vs. covalent bonds form, or how electronegativity plays a role!
Parent Tip: Review the logic above to help your child master the concept of covalent and ionic bonding worksheet.
