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Is it correct to say that heat is electrons gaining energy and light is electrons losing kinetic energy?

If this is correct is there a simpler way to explain a quanta? I get that it’s a small packet of energy but what does that mean?
I see where I was wrong in trying to simplify a connection between light and heat.
With quantum energy levels I guess I don’t see the significance of integral multiples; was there ever a real explanation prior to Planck’s Quantum Theory? When an electron emits or absorbs a quanta of energy is it a constant emission or is it in bursts’?


  1. No. That is not correct. Thermal energy (heat) results in the increase of molecular motion. When heated, molecules move faster, rotate faster and vibrate faster. It takes more than routine thermal energy to give an electron enough energy to change energy levels. That requires energy in the UV, visible and high infrared parts of the electromagnetic spectrum.
    It is important to realize that energy is not contiguous. When examining the energy given off or absorbed by electrons in atoms you will notice gaps. All of the energies turn out to be multiples of a lowest energy. That lowest energy is a quantum of energy.

  2. A photon, the quantum of light, is the smallest bit [of a given frequency] you can have, just like one atom of gold is the smallest bit of gold you can have.
    Photons are released when an electron falls to a lower energy level, but also when any charged particles are accelerated [see free electron laser]
    Heat in solids can manifest in several ways. [I am writing in terms of the heat in a hot lump of steel that is not there when the steel is cold; I am not talking in terms of radiant heat, infrared photons.]
    Not only do molecules vibrate, but the various vibration modes carry energy and at quantized levels. Bonds can stretch/shrink [a longitudinal vibration] and they can bend [transverse oscillation]. The angles between bonds coming into an atom can oscillate; think of a water molecule straightening out and then getting more bent.
    Energy shows up in rotation as well; in toluene, methyl benzene, the methyl group can rotate around the axis defined by the bond between the carbon of the methyl group and the carbon on the benzene ring to which it is attached.
    In conductors the electrons start whipping around.
    In ionic solids, the distances between ions can oscillate. THis vibration is quantized and has energy levels.
    THese vibration modes and their associated energies follow certain rules about what wiggles how much relative to the other modes, at least at thermal equilibrium, and all this wiggling is the energy of heat.

  3. No, that is not correct. When speaking of quanta we are referring to units as first defined by Planck in the quantum theory of radiation. Each oscillator does not have an energy that can take on any value from zero to infinity, but instead only discrete values:
    where ε’ is a discrete, finite amount, or quantum of energy and n is an integer.
    Essentially the emission and absorption of radiation must be discontinuous processes. Emission can only take place when an oscillator make a discontinuous transition from a state in which is has one particular energy to another state in which it has another energy different from the first by an amount which is an integral multiple of hν.
    Any physical system capable of emitting or absorbing electromagnetic radiation is limited to a discrete set of possible energy values or levels; energies intermediate between these allowed values simply do not occur. This applies to all energy systems including energy states of particles in atoms.
    You might also want to look into the Stefan-Boltzmann law as well…
    Hope that helped a little. Good luck.


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