Physical Science / Unit 4: Chemical Bonds and Compounds
4.6 Properties of Compounds
Notes
Bond type explains many properties.
| Property | Ionic | Covalent (molecular) |
|---|---|---|
| Melting point | High | Low |
| Solid conducts electricity | No | No |
| Dissolved or melted conducts | Yes | Usually no |
| Typical example | NaCl | Sugar, water |
- Metallic bonds: metal atoms share a "sea" of free electrons, making metals good conductors that can be bent (malleable) and drawn into wire (ductile).
- Ionic crystals are brittle: shifting the layers lines up like charges, which repel and break the crystal.
Practice
A white solid has a very high melting point and conducts electricity only when dissolved in water. It is most likely:
These are classic ionic properties.
Why are metals good conductors of electricity?
Metallic bonds have a sea of mobile electrons.
Which substance would most likely have the lowest melting point?
Molecular covalent compounds usually have low melting points.
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