Simple Covalent Molecules and Their Properties
Simple covalent molecules are substances made up of a small number of atoms held together by strong covalent bonds. These molecules have distinct properties due to their small size and how they interact with each other.
What is a simple covalent molecule?
A simple covalent molecule contains only a few atoms bonded by covalent bonds.
Examples include:
- Hydrogen (H₂)
- Oxygen (O₂)
- Carbon dioxide (CO₂)
- Water (H₂O)
- Methane (CH₄)
These molecules have strong bonds within each molecule, but they are not part of a giant structure.
Bonding and structure
- Each atom shares electrons to form covalent bonds
- These bonds are strong and hold the atoms together
- The molecules are held together by weak intermolecular forces
Properties of simple covalent molecules
Property | Explanation |
Low melting and boiling points | Weak forces between molecules are easy to break |
Do not conduct electricity | No free electrons or charged particles to carry current |
Usually gases or liquids | At room temperature, due to low intermolecular forces |
Insoluble in water (some) | Many do not dissolve easily in water – depends on polarity |
💡 Covalent bonds inside the molecules are strong, but the forces between molecules are weak, which explains the low melting and boiling points.
Melting and boiling points
The larger the molecule, the stronger the intermolecular forces, so:
- More energy is needed to overcome the forces
- This results in higher melting/boiling points for larger molecules
Questions
- What type of bonds hold the atoms together in a simple molecule?
- Why do simple molecules have low boiling points?
- Do simple covalent molecules conduct electricity?
- What happens to boiling points as molecules get bigger?
- Give two examples of simple covalent molecules.
Summary
- Simple covalent molecules are made of a few atoms joined by strong covalent bonds
- They have weak forces between molecules, called intermolecular forces
- These substances have low melting and boiling points
- They do not conduct electricity because they have no free electrons or ions
- Many are gases or liquids at room temperature