Covalent Bonding
- Created by: iloverevision:)
- Created on: 18-03-19 17:35
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- Covalent Bonding
- Molecules
- form when 2 or more atoms bond together
- held together by strong covalent bonds
- can be single, double or triple bonds
- single bonds
- 2 atoms share electrons so they have both got full outer shell
- 1 shared pair of electrons
- both positive nuclei are attracted electrostatically to shared electrons
- e.g. I2, HCl, H2, CH4
- double & triple bonds
- shown using multiple lines
- 1 carbon atom bonds to 2 oxygen atoms. Each carbon atom has to form 4 bonds. 2 double bonds are formed
- single bonds
- can be single, double or triple bonds
- simple covalent compounds
- made up of lots of individual molecules
- atoms in molecules held together by intermolecular forces
- determine properties
- in general, low melting & boiling points & electrical insulators
- determine properties
- atoms in molecules held together by intermolecular forces
- made up of lots of individual molecules
- Giant Covalent Structures
- type of crystal structure
- huge network of covalently bonded atoms
- aka macromolecular
- graphite
- carbon atoms arranged in sheets of flat hexagons covalently bonded with 3 bonds each
- 4th outer electron of each carbon is delocalised
- sheets are bonded together by weak van der Waals forces
- properties
- slippery & used in dry lubricants
- weak bonds between layers are easily broken so sheets can slide over eachother
- electrical conductor
- delocalised electrons free to move so electrical current can flow
- high melting point - over 3900k
- strong covalent bonds
- insoluble in a solvent
- covalent bonds in sheets too difficult to break
- slippery & used in dry lubricants
- low density - used to make strong lightweight sports equipment
- layers are quite far apart compared to length of covalent bonds
- carbon atoms arranged in sheets of flat hexagons covalently bonded with 3 bonds each
- diamond
- each carbon atom bonded to 4 other carbon atoms
- tetrahedral shape
- properties
- high melting point
- over 3800k due to lots of covalent bonds needing to be broken
- extremely hard
- used in diamond tipped saws & drills
- good thermal conductor
- vibrations travel through the stiff lattice easily
- can't conduct electricity
- all outer electrons are held in localised bonds
- like graphite, won't dissolve in any solvent
- high melting point
- Co-ordinate (dative covalent) bonds
- one of the atoms provide both of the shared electrons
- e.g. ammonium ion
- nitrogen atom in an ammonia molecule donates a pair of electrons to a hydrogen ion
- forms when 1 of the atoms in the bond has a lone pair of electrons & the other doesn't have any electrons available to share
- Molecules
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