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Physics

 

            In Newton's time the atom was thought to be a small hard indestructible sphere, this was a good model for the kinetic theory of gasses, but new models had to be developed in order to explain the electric nature of atoms.
             Ernest Rutherford and a couple of his students in 1911 performed an experiment where they shot positively charged alpha particles at a piece of foil and interesting enough the most of the alpha particles passed right through the foil and some bounced back.
             This lead Rutherford to conclude his planetary model, although a good model but it does have a couple problems.
             Ch28.2 If a gas is put into an empty tube at very low pressure and a voltage is applied between two metal electrodes that cause a current to flow through the gas a light will be emitted which is unique to the gas in the tube.
             When the light is analyzed through a spectrometer a certain series of discrete lines of color are observed each corresponding to a different wave length. The series of lines is called an emission spectrum.
             Wave lengths of the less prominent lines can be expressed in the equation 1/l=Rh(1/2^2-1/n^2) where n may have values of 3,4,5 . Rh=1.097E7.
             Also an element can also absorb light at specific wavelengths known as the absorption spectrum.
             The absorption spectrum has many practical applications.
             Ch28.5 On of the postulates made by bohr in this theory of the hydrogen atom was the angular momentum of the electron is quantized in units of h=h/2pie of mevr=mh.
             The reason angular momentum is restricted t certain values is because the condition fro a de Broglie standing wave in an electron orbit is that the circumference must contain an integral multiple pf electron wavelengths.
             Ch28.6 In addition to the principle quantum number two other quantum numbers emerged from the solution of the wave equation l and m the number l is called the orbital quantum number, and m is called the orbital magnetic quantum number.


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