3.2 & 3.4

3.2: Atomic spectra:

  • spectrum not completely continuous

  • Fraunhofer Lines: a set of dark lines in the otherwise continuous solar spectrum

  • Atomic emission spectra: characteristic patterns of bright lines produced when atoms are vaporized in high-temperature flames or electrical discharges

  • Atomic absorption spectra: characteristic patterns of dark lines produced when an external source of radiation passes through free gaseous atoms.

  • Explanation of franuhofer lines: gaseous atoms in outer regions of sun absorb characteristic wavelengths of sunlight passing through them on its way to earth


  • 3.4: The hydrogen Spectrum and the Bohr Model:


3.4: The hydrogen spectrum and the Bohr model:

  • Balmer’s equation is called the empirical equation

  • the left value on Rydberg’s equation is called the wavenumber (1/lambda)

  • Rydberg’s constant RH = 1.0974 × 10^7 m^-1

  • Advantage of Rydberg’s equation was that allowed scientists to predict the wavelengths of other series of hydrogen emission lines for which N1 does not equal 2

  • Discrete energy levels were in the atom

  • Niels Bohr: proposed a model for hydrogen atoms where the electron revolves around the nucleus in one of an arrays of concentric orbits

  • When negatively charged electron orbiting around the positively charged nucleus, the electrostatic potential energy between these two charges depends on the product of the charges on each particle divided by the difference between them.

    • Energies become less negative if the distance between the particles becomes greater

      • Happens if electron moves to an orbit with a greater n value

    • As values of n orbits farther from the nucleus approaches infinity, and E approaches zero

    • Xero energy means that the electron is at infinity and no longer part of the hydrogen atom

  • Important denature of Bohr model can explain a theoretical framework for explaining the observation of Balmer, Rydberg, and others

  • As n increases, the size of orbit increases, and so does the distance between the nucleus and electron.

  • D increases = E increases (becomes negative)

  • n decreases = size of electrons orbit decreases = distance between nucleus and electron decreases

  • Ground state: the most stable, lowest-energy state of a particle

    • Bohr model: electron cannot have any less energy than it has in the ground state, means cannot lose more energy and spiral in the nucleus

  • n=1 atom said to be in excited state: any energy state above the ground state

  • Electron transition: movement of an electron between energy levels