Chemical Bonding II Flashcards
Describe sp3 hybridization
One 2s and three 2p orbitals mixtoform 4 sp3 orbitals
Have 0 unhybridised p orbitals
Form when 4 sigma and 0 pi bonds are present
Electron pair geometry of sp3 orbitals
To minimise interelectronic repulsion, sp3 orbitals orientate themselves im the tetrahedral shape with bond angle of 109.5
Describe sp2 hybridization
One 2s and two 2p orbitals mixtoform 3 sp2 orbitals
Has 1 unhybridised p orbitals
Form when 3 sigma and 1 pi bonds are present
Election pair geometry of sp2 orbitals
Sp2 orbitals orientate intrigonal planar shape with 120 bond angle to minimize interelectronic repulsion
Describe sp hybridisation
One 2s and one 2p orbitals mixtoform 2 sp orbitals
Has 2 unhybridised p orbitals
Form when 2 sigma and 2 pi bonds are present
Election pair geometry of sp hybridization
To minimise interelectronic repulsion, sp orbitals orientate themselves in linear geometry with 180 bond angle
S character of each hybrid orbital
sp3 = 25%
sp2 = 33%
sp = 50%
Effect of hybridization on bond length and bond strength
The higher the s-character of hybrid orbital, the less diffuse the hybrid orbital, the more tightly the shared electrons are held by the nuclei, the more effective its overlap with the orbital of the other atom, the stronger the bond, the shorter its bond length
Describe resonance
A molecule exhibits resonance when there is continuous side on overlap of unhybridised portals of at least 3 adjacent atoms and allow for delocalisation of pi electrons
Describe structure of diamond
Each carbon atoms is sp3 hybridized and covalently bonded to 4 other carbon atoms arranged tetrahedrally around it
Structure of graphite
I. Has layer structure and is made up of planes of interconnected hexagonal rings of carbon atoms
2. Each carbon atom is sp2 hybridized and forms 3 sigma bonds with three other carbon
3. The electron pair geometry is trigonal planar with bond angles of 120° around each carbon atom
Howis graphite a electrical conductor
each cartoon has an unhybridised p orbital which contain a single
electron
P orbital of one carbon atom overlaps continuously with p orbitals of the neighboring atoms forming an extended pi electron cloud above and below the plane
The pi elections are delocalised over the whole layer and are free to more around to carry charges
What direction does graphite conduct electricity in
Graphite can only conduct electricity in a direction parallel to the layers as the pi electrons are only delocalised within each layer
Why does graphite have alliguer meting point than in diamond interns of structure of bonding
In diamond, the carbon atoms are sp3 hybridised while in graphite, the carbon atoms are sp2 hybridised
Each carbon atom in graphite has unhybridised p orbital containing one elctron each, can overlap collaterally with p orbitals of its immediate neighbour, additional electron density between carbon atoms, holds nuclei more closely, C-C bond is stronger
Hybrid orbitals of the carbon atoms in graphite have higher s vharacter, less diffuse, overlap of sp2 hybrid orbitals more effective than overlap of sp3 hybrid orbitals
Structure of quartz (silicon dioxide)
Each silicon atom is covalently bonded to four oxygen atoms tetrahedrally, each oxygen is bonded to two silicon atoms
Oxygen atom between each pair of silicon atoms
