Covalent bonding Flashcards
What is a covalent bond?
Shared pair of electrons between two non-metals.
Pair of electrons in an atom not used up for covalent bonds are called what?
Lone pairs
What is an expansion of the Octet?
When an atom uses all the electrons in the 3d subshell form covalent bonds regardless of whether the atom ends up with a noble gas electronic configuration or not.
What is a dative/co-ordinate bond?
When a lone pair of electrons are used to form a covalent bond. The two electrons come from the same atom instead if different.
Dative/co-ordinate bond has the same what as covalent bonds?
- Length
2. Strength (average bond enthalapy)
The acceptor ion in a dative/co-ordinate bond must be what?
Electron deficient (have spaces for those electrons).
How do u show a dative/co-ordinate bond?
- ->
eg. NH3 –> H
Shapes of molecules are based on what fact?
Electron pairs repel each other and move as part apart from each other as possible in order to minimise replusion.
Give shape name and angle for 2 total pairs
Linear 180*
Give shape name and angle for 3 total pairs
Trigonal planar 120*
Give shape name and angle for 4 total pairs
Tetrahedron 109.5*
Give shape name and angle for 5 total pairs
Trigonal bipyramidal 90/120*
Give shape name and angle for 6 total pairs
Octahedral 90*
What effect does lone pair have on bond angles and why?
Lone pairs repel more strongly than bonding pairs so each pair reduces the bonding angle by 2.5
Overall how to do the shape of molecules: (3steps)
- Find the base shape according to the total no. of pairs.
- Reduce the angles according to lone pairs.
- Ignore the lone pairs and find a new name of shape with the modified angles.