Ionization Energies Calculation

[Integral0]

How do you go about calculating the ionization energies from atoms?
Electron affinities? (KJ/mol)
for example,

"Calculate the change in energy from the first and fourth ionization energies of Be?"

Recently on a test (CHEM AP HIGH SCHOOL), I had a question similar to this on an exam. I got it wrong b/c I believe that bohr's equation only worked for Hydrogen atoms.

E = -2.178 x 10^-18 J (z^2/n^2)

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Please do not include upper level (meaning above the level of an introductory course in chemistry) material that would enable the calcuations. Please include introductory level "ways" to the change in ionization energies.

Thank you

 

[GCT]

The Bohr's equation only applies to hydrogen atoms. Actually it applies to hydrogen electrons and in this sense it is not directly related to ionization energies. In regards to a standardized equation which applies to all elements giving a quantitative value for ionization energies...I don't believe that this is in scope of high school ap chemistry.

The only equation which I can think of at this moment is that of nuclear effective charge. Which can only give you an idea of the relative values of first, second, third, fourth ionization energies. You are probably leaving out some information here which the test included. You can also use Columb's law, but you need to know the radius of Be.

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http://groups.msn.com/GeneralChemistryHomework

 

[ravenprp]

for your question. Calculating ionization energies and electron affinities can be done using basic principles of atomic structure and energy levels. Here are some steps to follow when calculating these values:

1. Understand the concept of ionization energy: Ionization energy is the amount of energy required to remove an electron from an atom or molecule in its gaseous state. The ionization energy increases as you remove each successive electron from an atom.

2. Determine the atomic structure: To calculate ionization energies, you need to know the atomic structure of the element in question. This includes the number of protons, neutrons, and electrons in the atom.

3. Use the Bohr model: The Bohr model, although not entirely accurate, is a useful tool for calculating ionization energies in introductory chemistry. It states that the energy of an electron in an atom is proportional to its distance from the nucleus. The equation you mentioned, E = -2.178 x 10^-18 J (z^2/n^2), is derived from the Bohr model and is used to calculate the energy of an electron in a hydrogen atom. While it may not be accurate for other elements, it can still provide a general idea of the energy levels of electrons.

4. Calculate the first ionization energy: To calculate the first ionization energy, you need to know the energy level of the electron being removed. For example, if you are calculating the first ionization energy of beryllium (Be), you would use the equation E = -2.178 x 10^-18 J (4^2/1^2), since beryllium has 4 protons and the first electron being removed is in the first energy level.

5. Calculate the subsequent ionization energies: To calculate the second ionization energy, you would use the same equation but with a different energy level for the electron being removed. For beryllium, the second ionization energy would be E = -2.178 x 10^-18 J (4^2/2^2), since the second electron being removed is in the second energy level. The third ionization energy would be E = -2.178 x 10^-18 J (4^2/3^2), and so on.

6. Calculate the change in energy: To calculate the change in energy between the first and fourth ionization energies of beryllium, you would simply subtract the fourth