Giant Covalent Substances Flashcards
Covalent Bonding
Covalent bonding lead to the formation of molecules. These can be:
Simple Molecules - which contains a set number of atoms joined by covalent bonds.
Giant Covalent substances - which contains many atoms joined by covalent bonding.
Key Properties
High Melting and Boiling Points: As the Covalent bonds are so strong, a lot of energy is needed to break them apart during melting and boiling.
Giant Covalent substances are solid at room temperature.
Conducting: They have no overall charge so most cannot conduct electricity as there are no moving charged particles. But Graphite is the only exception.
Insoluble in Water.
Diamond and Graphite
They are the different forms of Carbon. They both consist of a giant covalent network (repeating covalent sequence) structure of carbon atoms, joined together by covalent bonds.
But their shapes and properties were different.
Diamond: Structure and Bonding
Each carbon atom is joined together with 4 other carbon atoms by covalent bonding.
No Free Electrons.
Forms a tetrahedral network structure.
Diamond: Properties and Uses
The diamond is very hard due to the strong covalent bonding. Makes it useful in cutting tools.
Graphite: Structure and Bonding
Each Carbon atom is joined with three other carbon atoms by covalent bonds.
Forms a hexagonal layered network structure.
Layers have weak forces in between them so they can slide over each other.
Each carbon atom has a delocalised (electrons that are not associated with a particular atom) electrons and are free to move.
Graphite: Properties
Can conduct electricity due the delocalised electrons which are free to move around. Makes it useful for electrodes in batteries.
Can be used as a lubricant as the easily sliding layers makes the graphite slippery.
Graphene
Another form of Carbon.
Structure resembles a single layer of graphite.
High melting point and is very strong due to its large regular arrangement of atoms bonded by covalent bonds.
Can conduct electricity due to its delocalised electrons.
Fullerenes
A molecular form of the element Carbon. Two examples of fullerenes would be Nanotube and Buckyballs.
Nanotube
Resembles a layer of graphene but rolled into a tube.
High tensile strength (can withstand tension without breaking) so can resist being stretched.
Strong and conducts electricity due to its delocalised cells.
Buckyballs
Has 60 carbon atoms joined by covalent bonds
Weaker intermolecular forces, little energy to overcome, so they are slippery and have low melting points.
