Giant Covalent and Metallic Structures
Giant Covalent and Metallic Structures
Giant Covalent Structures
- Giant covalent structures, also known as macromolecular structures, are substances where all the atoms are covalently bonded to each other in a continuous network.
- Examples of giant covalent structures include diamond, graphite, silica (silicon dioxide) and many others.
- These structures can be complex but tend to form repeating patterns. Each atom is covalently bonded to its nearest neighbours.
Properties
- Due to the many strong covalent bonds, giant covalent structures are typically very hard.
- They also have high melting and boiling points because a lot of energy is required to break the many strong covalent bonds.
- Diamond and silica are examples of giant covalent structures that do not conduct electricity. This is because all their valence electrons are involved in bonding, and hence, they do not have free electrons to facilitate electrical conductivity.
- Graphite, on the other hand, is a special case that does conduct electricity along its layers because only three of the four outer shell electrons of the carbon atoms in it take part in bonding, leaving one electron free and delocalised between the layers.
Metallic Structures
- Metallic structures refer to the arrangement of atoms in a form of metals.
- Metals are arranged in closely-packed layers, with a sea of delocalised electrons moving through the structure.
- Metallic bonding is the force of attraction between these delocalised electrons and the positively charged metal ions.
Properties
- Metals have high melting and boiling points due to the strong forces of attractions present.
- They are generally malleable and ductile. These properties arise from the ability of the layers of atoms to slide over each other without breaking the metallic bonds.
- Metals are good conductors of heat and electricity due to the delocalised electrons, which are free to move and carry energy or charge.
- This metallic bond allows metals to form alloy with other metals which can modify the properties of the base metal.
Note: To deepen your understanding, consider creating diagrams of the giant covalent structures and metallic structures described. This will help you to visualise and remember their complex structures.