electron configuration

• frequency 


  the number of waves passing particular point per second - hertz(Hz)
• wavelength

  the distance between corresponding points of consecutive waves
• frequency = 1/wavelength
• the longer the wavelength, the lower the energy and frequency of the radiation, and the higher the frequency, the higher the energy
• white light is made up of light of all the colours of the visible spectrum
• photons 


  particle of electromagnetic radiation. the energy of a photon is proportional to the frequency of the electromagnetic radiation and inversely proportional to its wavelength
• A higher-energy photon corresponds to higher-frequency or shorter-wavelength electromagnetic radiation
• energy of photon =1/wavelength
• when hydrogen gas at low pressure is subjected to a very high voltage the gas glows pink
• the glowing gas can be looked at through a spectroscope, which contains a diffraction grating which separates the various wavelengths of light emitted from the gas
• emission spectrum

  electromagnetic radiation given out when an electron in an atom falls from a higher energy level to a lower one. only certain frequencies of electromagnetic radiation are emitted - a line spectrum
• each atom has a different emission spectrum
• hydrogen spectrum

  the emission spectrum in the visible region consists of a series of coloured lines that get closer together at higher frequency
• Although hydrogen is present as h2 molecules, collisions with high-energy electrons in the discharge tube cause the molecules to split up into H atoms
• the lines in an emission spectrum get closer together (converge) at higher frequencies and energies.
• each element has its own unique emission spectrum, and this can be used to identify the element
• line spectrum

  only certain frequencies and wavelengths of light are present
• continuous spectrum

  all frequencies and wavelengths of lights present
• which model provides an explanation of the lines in the hydrogen atom emission spectrum?

  bohr model of the atom
• bohr model of the atom

  Atoms consist of a central nucleus with electrons moving around the nucleus in circular orbits. The energy of an electron in a particular orbit is constant. Only certain orbits can exit, so the electron within an atom can only have certain amounts of energy
• the energy if an electron in a particular orbit is constant (energy levels )
• Only certain orbits can exist so that the electron within an atom can only have certain amounts of energy. These allowed energy levels are different for atoms of different elements.
• An electron in an orbit closer to the nucleus has lower energy than an electron in orbit further from thr nucleuse
• the energy levels are labeled with a number (n)
• n

  the principal quantum number
• the level closest to the nucleus has n=1 and the numbers increase as you go outwards from the nucleus
• ground state

  the lowest possible energy state for an atom
• excited state 


  an energy state for an atom that gas higheer energy than the ground state
• the electron in a hydrogen atom is usually in the lowest possible energy level closest to the nucleus - ground state
• passing an electric discharge through hydrogen gas causes an electron to be promoted to a higher energy level - excited state
• the electron is unstable in this higher level and will fall to a lower energy level
• when an electron falls from a higher to a lower energy level on an atom a photon of light is emitted
• As it moves from a level at energy e2 (higher energy) to E1 (lower energy), the extra energy (E2-E1) is given out in the form of a photon of light. This forms a line in the emmision spectrum
• Each line in the emission spectrum comes from the transition of an electron from a higher energy level to a lower energy level
• hydrom emmision spectrum lines

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• the line spectrum is evidence for energy levels for an electron in an atom
• why does a line spectrum show evidence for energy levels for an electron in an atom


  electrons in an atom are only allowed to have certain amounts of energy
• why isn't a continuous spectrum evidence for energy levels for an electron in an atom


  if an electron in an atom could have any amount of energy it could gain any amount of energy in a a discharge tube and give this energy again so that all frequencies of light would be emitted
• First ionization energy: The energy required to remove one mole of electrons from one mole of gaseous atoms
• Block organisation: s < p < d < f