Covalent Compounds Flashcards
What is a can covalent bond
Is a shared pair of electrons between atoms
What do covalent bonds occur in
- non metallic elements e.g. oxygen
- compounds of non metals e.g. sulphur dioxide
Are covalent bonds strong or weak
Strong
Covalent bond of H2O
H-O-H
Others have giant covalent structures e.g.
Diamond and silicon dioxide
Small molecules contain a relatively _______ number of non metal atoms joined together by covalent bonds
Small
The molecules have no overall electrical charge so they cannot ____________
Conduct electricity
What do substances that can consist of small molecules usually have ?
Low melting and boiling points
Why do substances consisting of small molecules have low melting and boiling points
Because the have weak intermolecular forces ( forces of attraction between the molecules)
The larger the molecules are :
The stronger the intermolecular forces between the molecule become
Bonds must be broken for the substance to
Melt or boil
Diamond is a form for f carbon it has :
- a giant, rigid covalent structure ( lattice )
- each carbon atom forms four strong covalent bonds with other carbon atoms
- all the strong covalent bonds mean that it is a very hard substance with a very high melting point
- there are no charged particles, so it does not conduct electricity
Graphite is another form of carbon and has :
- a giant covalent structure and a very high melting point
- each carbon atom forms three covalent bonds with other carbon atoms
- this results in a layered, hexagonal structure
- the layers are held together by weak intermolecular forces
- this means that the layers can slide past each other making graphite soft and slippery
One electron from each carbon atom is delocalised
These delocalised electrons allow graphite to conduct heat and electricity
