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Electrons energy levels do not change with molecular bonding

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  1. May 21, 2016 #1
    So if energy levels, or eV of electrons, do not change with molecular bonding, how are electrons influencing each other.?
    In glass, when individual atoms of silicon, sodium, and calcium come together, to form glass, the molecular bonding does not change the energy levels of the electrons for glass to transmission, light.
    Someone told me glass" the atoms, or electrons are influencing each other".
    What does influencing each other meanmean.
    What changes the eV of the electrons specifically for light to transmission, through glass.
    I am grateful for your help, anything helps even a few words.
     
  2. jcsd
  3. May 22, 2016 #2

    James Pelezo

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    Chemical bonding using the Valence Bond Theory of orbital hybridization and formation of Pi and Sigma bonds does (except for the very simple atomic ground states of Hydrogen) have to undergo changes in their valence level electron configurations in order to accommodate the appropriate particle-particle interactions. The transformations occur to form the most energetically favorable configuration for interacting elements.

    If this is along the line of your question/concerns as it relates to chemical bonding, I can add a bit more that could clarify the issue.

    From another point of view, if you are interested in the amorphous vs crystalline nature of material as it applies to chemical bonding and affects the transmission of light through the material, well that may follow studying concepts relating to properties of elements that bond leading to amorphous or crystalline glass that vary in light propagation. Or, I might be totally miss interpreting your question. Please add a bit more to your initial dialog and I'll see if I can respond to your concerns. Doc
     
  4. May 22, 2016 #3

    Borek

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    You are mistaking electrons not involved in bonding with valence electrons. Energies required to excite the latter electrons do change.

    You are asking all the time questions that clearly show you don't understand the basics. Please start with some General Chemistry or General Physics book, otherwise you are wasting your and our time. At the moment your questions are hard to address because they are off in many ways - you misuse the terminology, and you misunderstand properties of electrons, atoms, molecules and solids. We are not moving ahead.
     
  5. May 22, 2016 #4
    Silicon dioxide, which is the main component of common soda-lime glass is transparent in the visible spectrum, in most glasses you are dealing with oxides from the raw materials, not the elements individually.
    The image below shows a SiO2 (Quartz) crystal.
    roc-42.jpg
     
  6. May 22, 2016 #5
    Dear James, thank you for you answer,
    I just cannot seem to get the answers to the questions of what makes a electrons eV change whenatoms form molecules, and come together to form glass, for light to get transmission, through a solid object.
    Also can you list ALL the ways for electrons to be able increase, and decrease their eV to light absorption.
    Like heat, maybe microwaves, and maybe the electromotive force.
    Thank you so much.:smile:



     
  7. May 22, 2016 #6
    Dear, Borek, thanks for your answers,
    I just want to know how an electrons eV can be increased, or decreased with heat, electromotive force, or microwaves.
    Also what is the electrons eV when atoms form molecules to become glass, what is the eV of the electrons to transmission light.
    This is a easy question, its either known to science or not, the internet has no answer.
    But people just do not get to the point in their answers.
    I would rather them say its not known to science, or they do not know, then elaborate on something that is not to the point of what I am asking.
    I try to of think of new things to ask, farther than post the same thread.
    Thank you for your help.
     
  8. May 22, 2016 #7

    Borek

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    Sorry, but this question, as asked, doesn't make sense. That's what I am trying to tell you.
     
  9. May 22, 2016 #8

    James Pelezo

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    Mr Borek, would you clarify to whom this critique is directed? It comes right after my post. I am hoping it refers to the original post and not my post ... Just a bit confused here. Thanks
     
  10. May 22, 2016 #9

    Borek

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    It refers to the quoted post of OP.
     
  11. May 22, 2016 #10

    James Pelezo

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    Your questions seems to be in two parts, electron behavior and structural characteristics of compounds that account for light propagation properties. I will summarize basic electron behavior as it applies to absorption of light (Electromagnetic Radiation = EMR).

    In the study of electron behavior, it has been determined that electrons can gain and release electromagnetic radiation (EMR light) as well as function as a particle with finite rest mass and dimensional properties. This is generally referred to as the 'Wave - Particle Duality of the Electron'. Using the Bohr 'Concentric Ring' Theory of the atom, it can be shown that when Hydrogen gas is confined inside of a glass tube fitted with metallic conductors at each end and connected to a transformer, the gas will have a lavender glow. When this lavender glowing is observed through a spectroscope or diffraction grating, one sees three bright color lines. (Actually there are 4 lines, but one is so close to the UV spectrum that it is difficult to see by most human eyes.) The question is, what causes the lines. Answer: electrons releasing all or part of absorbed EMR having very discrete energy values, frequencies and wavelengths. These 'discrete' EMR events are called 'energy packets, or photons'. Each photon has a specific energy, frequency and wavelength. The basic calculations for energy change, frequency and wavelength can be found in reviews on the Bohr Concentric Ring model of the atom. Considering the Hydrogen atom, as you may already know, the most abundant form of the element has one proton and one electron. When the hydrogen atom is considered with the electron in the 1st energy level (ring), it is said to be in its 'ground state'. However, due to the electrons wave-particle duality, absorption of EMR will cause the electron to leave the 1st energy level and move to a higher energy level (absorption spectrum). Assuming the electron does not completely leave the atomic environment (ionization), the electron then releases part or all of the absorbed EMR energy and falls back toward the nucleus. However, it is important to note that the electron can only fall (transition) between energy levels and does not stop in between energy levels. This results in a specific amount of energy being released and is referred to as a 'quantum' leap or jump. If the electron transitions from a higher energy level and stops in the 2nd energy level, the energy given off can be seen as a 'bright line spectrum'. All atoms have unique bright line spectra that can be used to identify the element. In the case of the Hydrogen atom, the spectrum consists of a Red Line, Green Line, Blue Line and Violet Line. The Red line is an n = 3 to 2 transition, Green is an n = 4 to 2 transition, Blue is an n = 5 to 2 transition and Violet is a n = 6 to 2 transition. Electrons that stop at n = 3 or n = 1 can not be seen with the human eye. Those stopping at n = 3 are Infrared Transitions and those stopping at n = 1 are Ultra Violet Transitions. Electrons are in constant motion by sweeping out designated orbitals based upon their energy content and proximity to the nucleus. It is interesting to note that electrons associated with the more complex elements do not collide with one another, but exist within their own 'energy window' that prevents any other electron from occupying the same space. (Pauli Exclusion Principle). I hope this helps a bit... I have posted summaries of how valence electrons undergo changes in energy content to form pre-bonding hybrid orbitals that account for the molecular geometry of substances. Such can be extended into chemical bonding and related to structural characteristics that give the compounds formed their chemical and physical properties. Again, I hope this helps. Doc
     
  12. May 22, 2016 #11

    James Pelezo

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    Whew! Thank you.
     
  13. May 22, 2016 #12

    James Pelezo

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    Just an add-on FYI on bonding and bonding energies in science ... Generally, there are three types of bonding forces known, Physical Bonds, Chemical Bonds and Nuclear Bonds...Physical Bonds account for 'states of matter'; i.e., solids, liquid or gas. Individual bonding energies are typically very weak and are easy to break with low-energy input. Changes in state do not affect the chemical make-up of the substance. Chemical bondsare valence level interactions between elements. Chemical bonding energy depends upon the elements involved and their elemental properties. For example, a Carbon - Carbon 'single' bond ( C-C ) bond energy ~350 Kj/mol (~heat and light energy from a common wax candle), a 'double bond' ( C=C ) bond energy ~ 600 Kj/mol and a 'triple bond' ( C≡C ) bond energy ~ 835 Kj/mol. The larger numbers are the stronger bonds. It is important to note that the energy given up on bond formation is exactly equal to the amount of energy needed to break the bond. Change elements bonding and the bonding energy of the combination changes. Nuclear bonds are interactions between subnuclear particles;i.e., protons and neutrons. Bonding energies for nuclear level interactions are commonly referred to as 'Binding Energy per Nucleon' and expressed as Mega-electron-volt (MeV) values. (1.0 MeV = 1.6 x 10-16Kj). This means, the binding energy per nucleon equals the total bonding energy of all nucleons divided by the total number of neutrons and protons making up the nucleus. Nuclear bonding energies are also referred to as the 'Mass Defect' on formation of a nucleus. That is, Mass Defect is the amount of nuclear material converted into energy on formation of a nucleus. Mathematically, this is defined by the famous Einstein Equation ΔE = Δmc2 where Δm is the mass defect and c is the speed of light (3 x 108 m/s). Molar level Nuclear Binding Energies run in the 108th Kj/mol; e.g., atomic bomb levels. Quite a jump from a burning candle. Also, the energy of the sun is nuclear fusion where 'heavy' hydrogen atoms collide forming Helium + lots of sunshine. Doc
     
  14. May 23, 2016 #13
    Thank you for your answer, really helped a lot.
    Also so the eV levels are not known for glass, is the number in eV not known to science.
    Is it because it is too discernable/ complex, to get.
    Do you know the answer to this question.
    Thank you for your help


     
  15. May 23, 2016 #14
    The binding energies of electrons are known for most materials, for many solids, you get bands forming from the hybridization of orbitals and the many-electron characteristics of these materials for the valence electrons. In this case it doesn't make sense to talk of binding energies for a particular electron like it does for hydrogen. For such materials, there can be an energy gap between the bottom of the conduction band and the top of the valence band, and electrons cannot have energies within this gap. It is this energy gap (the band gap) in semiconductors and many insulators which determines when a material directly absorbs light, by promoting an electron from the valence to conduction band. I.e. the light has to have energy equal to or greater than the band gap of the material.

    Glasses are a bit more complicated, as they are amorphous, which allows them to have some states in the energy gap, however, they still behave quite like the crystalline equivalent.

    An example of the valence band structure and how they can vary with similar materials is shown in the figure below. The valence band is directly measurable using photoelectron spectroscopy methods, or can be predicted using density functional theory, and compared to experimental results as per the figure below from S. Vasheghani Farahani et al. Physical Review B 90(15):155413
    Figure-3Comparison-of-the-cross-section-weighted-DFT-PDOS-with-the.png

    Photoelectron spectroscopy can also be used to measure glass samples, as in this paper. Here, figure 2 shows the valence band as measured by XPS for a slightly exotic glass. Equally slide 12 here, shows multiple electronic states occurring in another type of glass for the electrons not involved in the bonding.
     
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