DepEd MELC reviewer for Grade 9 Science, Quarter 2. Master the concepts, tables, and common-mistake warnings below.
1
Why Atoms Bond
Atoms bond to achieve a stable octet (8 valence electrons). Valence electrons are those in the outermost shell.
2
Types of Bonds
| Bond | How | Example |
|---|---|---|
| Ionic | Metal transfers e⁻ to nonmetal | NaCl |
| Covalent | Nonmetals share e⁻ | H₂O |
| Metallic | Sea of shared electrons | Cu, Fe |
⚠️ Common Mistake
Metal + nonmetal → IONIC (transfer). Nonmetal + nonmetal → COVALENT (share).
3
Properties from Bonding
Ionic compounds have high melting points and conduct when dissolved; covalent compounds are often gases/liquids with low melting points.
4
Predicting Bond Type
| Combination | Bond |
|---|---|
| Na + Cl | Ionic |
| H + O | Covalent |
| Fe + Fe | Metallic |
⚠️ Common Mistake
Check the periodic table: metals are on the left, nonmetals on the right.
📌 Quick Recap — Master These
Before your test, make sure you can confidently do each of the following:
- Explain and apply Why Atoms Bond.
- Explain and apply Types of Bonds.
- Explain and apply Properties from Bonding.
- Explain and apply Predicting Bond Type.
Re-read any section above where you hesitate, then try the worked example again without looking.