Covalent bonding Flashcards
How is a covalent bond formed
A covalent bond is formed between two non-metal atoms by sharing a pair of electrons in order to fill the outer shell.
Covalent Bonding
A strong attraction between a shared pair of electrons and two nuclei.
Dot and cross diagrams
Book
Why substances with a simple molecular structures have low boiling and melting point
They have low boiling and melting point because to boil simple covalent molecules, it only has to break weak intermolecular forces. So they need little energy to break these weak bonds.
Why melting and boiling point increases with increasing relative molecular mass?
Melting and boiling points increases because the higher mass the higher boiling point because as bigger the mass there is going to be more intermolecular forces that have to be broken whith more energy.
Why substances with giant covalent structures have high melting and boiling point?
Because it is a giant covalent structure with many strong covalent bonds. that require a lot of energy to break.
Does covalent compounds conduct electricity?
No, usually the do not conduct electricity
Dimond
In dimond each carbon atom forms 4 covalent bonds to 4 other atoms . A giant lattice structure forms. Dimond has a high melting point because it has strong covalent bonds that require a lot of energy to be broken down. Dimond, does not conduct electricity as there are no delocalised / free electrons.
Graphite
- Graphite atom forms 3 covalent bonds to 3 other atoms. A 2d layer of hexagonal rings of carbon atom forms.
- It has a high melting point as graphite has strong covalent bonds that need to be broke down requiring a lot of energy.
- This layers are held by weak intermolecular forces (van de Waals).
- Graphite is used as a dry lubricant. It can conduct electricity.
Fullerene (C60)
- Weak intermolecular forces of attraction
- Can not conduct electricity although it has delocalised molecules because electrons can not jump between different molecules
