1.5 Solid structures Flashcards
What are ionic solids made up of?
Oppositely charges ions packed around each other.
What is the arrangement of Sodium Chloride?
Each Na+ is surrounded by 6 Cl- and each Cl- is surrounded by 6 Na+. Therefore the crystal coordination number is 6:6
What is the arrangement of Caesium Chloride?
The number of oppositely charged ions surrounding each ion is eight. Therefore it has a crystal coordination number of 8:8. This crystal is larger therefore can accommodate a larger number of atoms
What are the general properties of ionic compounds?
- high melting points due to strong electrostatic attraction between ions
- Electrical conductors as molten or dissolved in water as ions are free to move and carry charge
- Brittle sure to repulsion between charged ions
What are giant covalent structures?
Atoms that form multiple bonds to other atoms forming a giant lattice structure
Describe the structure of diamond
Form of the element carbon. each carbon bonds strongly to 4 other carbons in a tetrahedral arrangement to form a 3D structure.
Describe the structure of graphite
Although carbon can form 4 bonds, in graphite only three bonds are made. Hexagonal layers are formed that are held together by6 weak Van der Waal’s forces
What are the properties of diamond?
- high melting point
- insoluble in water
- very hard
- electrical insulator
What are the properties of graphite?
- high melting point
- insoluble in water
- soft and slippery
- electrical conductor
What do simple covalent structures consist of?
Simple covalent molecules held together in a lattice by weak intermolecular forces.
What are the properties of simple covalent structures?
- Low melting and boiling point due to weak intermolecular forces
- Soft due to weak intermolecular forces requiring only small force to break
- electrical insulators due to the lack of mobile charged particles
Describe the structure of a metallic structure
Regular arrangement of metal cations closely packed together surrounded by a sea of delocalised electrons
