How bonding and structure relate to the properties of substances Flashcards
Why do ionic substances have high melting points?
- Giant ionic lattice
- Strong electrostatic forces between ions
- Large amount of energy to overcome these forces
- High meting point
Why do metallic substances have high melting points?
- Made of positive metal ions in a sea of delocalised electrons
- Strong electrostatic forces between metal ions and delocalised electrons
- Large amounts of energy to overcome these forces
- High melting point
Why do simple covalent molecules have low melting points?
- Small molecules
- Weak intermolecular forces between molecules
- Small amounts of energy to overcome these forces
- Low melting point
Why do giant covalent structures have high melting points?
- Giant covalent lattice
- Strong intermolecular forces between molecules
- Lots of energy required to overcome forces
- High melting point
Why are metallic substances good at conducting heat/electricity
Delocalised electrons can flow through the structure and carry charge/energy
Why are alloys hard?
- Atoms are different sizes because of different elements
- Layers cannot slider over each other as easily when force is applied
- More forces required to make layers slide
- Hard
Why are pure metals softer than alloys?
- All atoms are same size because all atoms are the same element
- Layers can slide over each other more easily
- Less force required to make layers slide
- Softer than alloys
When can ionic substances conduct electricity?
- Molten
- Aqueous (dissolved in water)
Why can ionic substances conduct electricity when molten or aqueous?
Ions are free to move and carry charge
What is the only covalent structures that can conduct electricity?
Graphite and graphene
Why can graphite conduct electricity?
- Arranged in layers
- Delocalised electrons can flow through the layers and carry charge
