Bonding 1 Flashcards
Oxidation states
Helps keep track of the electro distribution between variius reactants and products in a chemical reaction
Element is oxidized when
The oxidation number of the element becomes more positive during s chemical reaction
Element becomes reduced when
The oxidation number becomes more negative during s chemical reaction
Ground state
When all electrons are in the lowest energy orbitals available
Closed shell
A condition referred to as an octet when considering s and p valence electrons
Valence Shell Electron Pair Repulsion (VSEPR) Theory
Predicts shape of simple molecules; one rule = electron pairs, whether bonding or non bonding, attempt to move as far apart as possible
Linear
A molecule with a 180 bond angle
Electron groups
Determine the atom’s geometric identity
2 electron groups
Linear
sp hybridization
3 electron groups
Trigonal planar
sp2 hybridization
4 electron groups
Tetrahedral
sp3 hybridization
5 electron groups
Triagonal bipyramidal
dsp3 hybridization
6 electron groups
Octahedral
d2sp3 hybridization
Determining molecular shape
- ) count number of electron groups = geometric family
2. ) determine shape based on non binding pairs
Determining hybridization
Orbitals always get used up s -> d; start left and work right until all orbitals are filled;
Hybridization of carbon on Methane = s+p+p+p = sp3
Covalent bond
Atoms attempt at closed shell stability; it is two atoms with similar electronegativities compromise to achieve octet
Nonpolar bonds
Covalent bonds in which the electron pair spends the same amount of time around each atom
Polar bonds
Covalent bonds that are fatter at one end than at the other
Band theory
Model in which the metal is thought of as a giant molecule in which delocalized molecular orbitals cover the entire structure
Continuous band
Formed when N molecular orbitals are very closely spaced in energy and form a band covering a range of energies
Valence band
Band that is the highest energy and contains freely moving valence electrons
Conduction band
The empty band that overlaps the valence band; if electrons jump into it the material will be able to conduct electricity
Band Theory point 1
When a valence band is not fully occupied, valence electrons can move in many energy states
Band theory point 2
Valence electrons can jump into the conduction band
Band theory point 3
The width of the band depends of the degree of overlap of the atomic orbitals between neighboring atoms: the greater the overlap the wider the band
Band theory point 4
A band is thus a near-continuum of finite number of energy levels
Band theory point 5
The band constructed from the overlap of s orbitals is called the s band. Similarly p bands and d bands can be constructed
Band theory point 6
A metal has overlapping valence and conduction band (VB and CB)
Band theory point 7
Insulators have a big gap between their VB and CB
Band theory point 8
A semiconductor has a small gap between the VB and CB; adding energy can then excite electrons that can jump from VB to CB
