Properties of Simple Molecular Compounds
Chemistry: Cambridge International GCSE Supplement, topic 2.5.5
Properties of Simple Molecular Compounds
Simple molecular compounds have strong covalent bonds within molecules but weak intermolecular forces between them. This leads to low melting/boiling points and poor electrical conductivity.
What are simple molecular compounds?
- Simple molecular compounds consist of small groups of atoms joined by covalent bonds.
- Each molecule is held together by strong covalent bonds.
- The molecules are separate and not connected to each other.
- The forces between molecules are called intermolecular forces.
- Intermolecular forces are much weaker than covalent bonds inside molecules.
Low melting and boiling points
- Simple molecular compounds have low melting and boiling points.
- The weak intermolecular forces need little energy to break.
- The strong covalent bonds inside molecules do not break during melting or boiling.
- Examples include water (H2O) and carbon dioxide (CO2).
- These compounds usually evaporate easily at room temperature.
Poor electrical conductivity
- Simple molecular compounds do not conduct electricity.
- Their molecules do not have free ions or electrons to carry charge.
- The strong covalent bonds keep electrons tightly in place.
- This is different from ionic or metallic compounds, which conduct electricity.
- Examples include sugar and oxygen gas (O2).
Summary of structure and properties
- Covalent bonds hold atoms inside molecules strongly.
- Weak intermolecular forces act between molecules.
- Low melting and boiling points result from breaking weak forces.
- No free charged particles cause poor electrical conductivity.
- These properties help identify simple molecular compounds in experiments.
Test yourself on Properties of Simple Molecular Compounds
Why do simple molecular compounds typically have low melting and boiling points?
What is the reason simple molecular compounds do not conduct electricity?