Ionization energy and speed of electron

In summary, a neon sign uses a gas discharge tube with neon gas at low pressure and metal electrodes to produce light. When a high voltage is applied, the electrons in the gas collide with the neon atoms and emit light. The required speed for an electron to eject another electron from a neon atom and produce light is either 1.436x10^4 m/s or 2.754x10^6 m/s, depending on the method used to calculate it. The correct solution is the one where the mass of an electron is substituted in for the value of m. The electrons being accelerated come from the neon gas itself.
  • #1
lkh1986
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A neon sign is a gas discharge tube in which electrons traveling from the cathode to anode collide with neon atoms in dicharge tube and knocks electrons off of them. As electrons return to the neon ions and drop to lower energy levels, light is given off. How fast would an electron have to be moving to eject an electron from an atom of neon,which has a first ionization energy of 2080KJ per mol.

OK, I got 2 set of solutions, buI don't know which one of them is the correct one, maybe neither is correct, too.

For solution number 1, I calculate the ionization energy for 1 atom of neon, by dividing 2080 by Avogadro number. Then, I get E. I obtain the mass of 1 atom of neon, by dividing its molar mass by Avogadro number, too. Using E= (1/2)(mv^2), i get the value of v=1.436x10^4 m/s.

For solution number 2, i do the same thing, except for the value of m, I substitute in the m for an electron. Finally, I get v=2.754x10^6 m/s.

Which one is the correct solution? Or neither? Thanks. :smile:
 
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  • #2
One solution is correct, the other is incorrect. Which do you think is which and why?
 
Last edited:
  • #3
I think the solution which I substitute the value of m equals the mass of an electron seems correct. My understanding of the situation of this problem is as such: the kinetic energy of the high-speed moving electron has been "changed" to the energy that is required to knock out an electron from a neon atom, which is later become te light energy.

May I know where the electron that are being accelerated comes from? Is it from the neon atom itself? Or it is "already there" in the discharge tube? Thanks.
 
  • #4
lkh1986 said:
I think the solution which I substitute the value of m equals the mass of an electron seems correct. My understanding of the situation of this problem is as such: the kinetic energy of the high-speed moving electron has been "changed" to the energy that is required to knock out an electron from a neon atom, which is later become te light energy.
Yes, the latter answer is correct.
May I know where the electron that are being accelerated comes from? Is it from the neon atom itself? Or it is "already there" in the discharge tube? Thanks.
A brief introduction from howstuffworks.com;
Howstuffworks said:
The idea behind a neon light is simple. Inside the glass tube there is a gas like neon, argon or krypton at low pressure. At both ends of the tube there are metal electrodes. When you apply a high voltage to the electrodes, the neon gas ionizes, and electrons flow through the gas. These electrons excite the neon atoms and cause them to emit light that we can see. Neon emits red light when energized in this way. Other gases emit other colors.
 

1. What is ionization energy and why is it important?

Ionization energy is the amount of energy required to remove an electron from an atom or molecule. This process is important because it plays a crucial role in chemical reactions and the formation of chemical bonds.

2. How is ionization energy related to the speed of electrons?

The ionization energy of an atom or molecule is directly related to the speed of its electrons. As the ionization energy increases, the speed of the electrons also increases. This is because it takes more energy to remove an electron that is moving at a higher speed.

3. Can the speed of an electron be faster than the speed of light?

No, according to Einstein's theory of relativity, the speed of light is the maximum speed at which anything can travel. Therefore, the speed of an electron cannot be faster than the speed of light.

4. Does ionization energy vary for different elements?

Yes, ionization energy varies for different elements. It generally increases from left to right across the periodic table, as the number of protons and electrons increases. It also decreases as you move down a group, as the electrons are farther from the nucleus and are easier to remove.

5. How is ionization energy measured?

Ionization energy is typically measured in units of kilojoules per mole (kJ/mol) or electron volts (eV). It can be measured experimentally using techniques such as mass spectrometry or through calculations using theoretical models.

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