Sample Question: Electron Spin and Orbital Angular Momentum
From atomic structure we know an electron can only have has an intrinsic spin vector of s = 1/2. From quantum mechanics the magnitude of the spin vector is ׀s׀ is, where h (h bar)…
Topics: Matrices
Magnetic Sector Mass Spectrometer
A cation of charge q travelling with a velocity v enters a magnetic field B at right angles (θ = 90°) to the field and experiences a magnetic force FM which is the vector product,…
Sample Question: Methane Structure
Methane is tetrahedral, that is it fits inside a cube with the carbon atom at the intersection of any two diagonals, which is at the origin (0, 0, 0), above Figure. Two hydrogen atoms sit…
HMO Theory for Cyclobutadiene
HMO theory is an approximate theory that gives a quick picture of the molecular orbital energy diagram of organic conjugated molecules. (a) Write down the Hiickel secular determinant for the four C-atoms of cyclobutadiene in…
Calculate Vector Addition Dipole Moments of Molecules?
Dipole moments occur when there is a separation of charge. When atoms in a molecule share electrons unequally, they create what is called a dipole moment. They can occur between two ions in an ionic…
Calculate the Absorption of Light by Polar Molecules?
It is possible to arrange molecules so that the bond dipoles all point in a particular direction. Below Figure shows the alignment of carbonyl bonds in a sample. The magnitude of the carbonyl dipole moment…
Time of Flight Mass Spectrometer
A time of flight (TOF) mass spectrometer is sketched below- The TOF MS is all under a vacuum. A pulsed laser fires a pulse of light onto a sample plate causing a pulse of ions…
Sample Question: Hydrogen Halide Dipole Moments
The magnitudes of the four hydrogen halide dipoles are given below. Firstly, using vector notation, express the magnitudes of the HF, HBr and the HI dipoles as scalar multiples of the HCI dipole magnitude. Secondly,…
Sample Question: HMO Theory for Cyclopropenyl Cation, Radical and Anion
Sample Question: HMO Theory for Cyclopropenyl Cation, Radical, and Anion. (a) Write down the Hiickel secular determinant for the cyclic three C-atoms in terms of x, where x = (α – E)/β. (b) Solve the…
Sample Question: HMO Theory for 1,3-Butadiene
(a) Write down the Hiickel secular determinant for the four C-atoms of butadiene in terms of x, where x = (α – E)/β. (b) Solve the secular determinant for x and then rewrite the solutions…
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