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Homework Help: Balmer series

  1. Jul 29, 2008 #1
    why do we see a discreet line spectrum from hydrogen gas?
  2. jcsd
  3. Jul 29, 2008 #2


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    If one takes a pure element and heats it, or ionizes it, one will see discrete emission lines.

    How are photons created? What does one know about the energy levels of electrons in atoms?
  4. Jul 29, 2008 #3
    why is it discreet and not continuous?

    I do not know the answers to your questions. please explain?
  5. Jul 30, 2008 #4


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  6. Jul 30, 2008 #5
    why does a blackbody emit a spectrum then?
  7. Jul 30, 2008 #6
    i read somewhere that "all objects emits thermal radiation characterized by a continuous distribution of wavelengths"

    why is this not true for pure metals?
  8. Jul 30, 2008 #7
    In a gas, the atoms are generally independent. The electron's energy levels are those that are characteristic of a particular atom here and another particular atom there, so you tend to get a discrete spectrum. But solids and liquids, and even a very dense gas such as in a star, have atoms so close together that they modify each other's energy levels, and fill in the gaps, so you get a continuous spectrum. Hold some sodium chloride crystals in a flame and you will see the famous "sodium yellow" color, but it's coming from the vapor that is boiling off.
  9. Jul 30, 2008 #8
    what about liquid nitrogen? nitrogen is a pure element, but you're saying since it is a liquid, it will emit a continuous spectrum? so you're saying if the nitrogen gas is very close together, it will modify each other's energy energy levels so to make a continuous spectrum?

    how would someone excite gas? can you excite gas the same way you excite solids and liquids? by heating them up?

    i read somewhere that you can put the gas in an electric field? why would this excite the gas?
  10. Jul 31, 2008 #9
    thanks for the comments so far. anyone have any thoughts on the above questions?
  11. Jul 31, 2008 #10
    Each line in the hydrogen emission spectrum corresponds to photons with different energies. If they were all the same then they would emit the same type of light. A low energy state corresponds to one in which the value of the energy is larger, the value of n smaller and the stability of the electron high. A high energy state corresponds to one in which the value of the energy of attraction, the value of n is larger the stability of the electron is low. Having said that, when you look at the hydrogen spectrum from a cathode-anode experiment with a spectrometer, you can see that ionization has occurred because of the discrete lines. But when you look at a light bulb it is continous. Why? Could it possibly have something to do with the energy states of the electron moving from one energy orbital to another?

    Keep thinking......
  12. Jul 31, 2008 #11
    a light bulb has electrons too... why wouldnt the electrons in the light bulb move from one energy orbital to another?
  13. Aug 1, 2008 #12
    would the answer be something that mikeplore said?

    if so, then this returns to my previous posts:

    still confused.
  14. Aug 4, 2008 #13
    why does heating a filament give a continuous spectrum? doesnt the filament have electrons orbiting a nucleus?
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