Giant Covalent Structures
- Made from carbon only
- Each carbon atom makes 3 covalent bonds to other atoms forming layers. The layers are only held together by weak forces, so slide over one another easily. So graphite feels soft and slippery.
- One electron from each carbon atom can move through the structure- it is delocalised. So graphite can conduct electricity.
Silicon Dioxide (Silica)
- Made from silicon and oxygen
- Each silica atom makes 4 covalent bonds to oxygen atoms
- Each oxygen makes 2 covalent bonds to silicon atoms
- High melting point
- Hard and strong
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- Strong forces of attraction (electrostatic forces) between the positively charged metal ions and the negatively charged sea of electrons hold the structure together
- The outer electrons from each atoms are delocalised- they can move through the structure forming a sea of electrons that hold the metal ions together.
- Metals conduct electricity because the outer electrons from each atom are delocalised so they can move through the structure.
- Metals are malleable because the layers of atoms can easily slide over one another
- Metals have a high melting point because there are strong forces forces of attraction between the molecules. So a large amount of energy is required to overcome these forces and melt the metal.
- The three types of bonding
- Covalent = non-metals only
- Ionic= a metal with a non-metal
- Metallic=Metal only
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