Ionization Energy

[Brian_Mena_1J]

For choosing a central atom for model it says to choose the atom with the least amount of ionization energy how would you determine this?

[Jared Faith 4E]

You can use the general ionization energy trend from the periodic table to find which atom has less ionization energy. Ionization energy (IE) decreases as you move left and down the Periodic Table. You can also use the opposite and say IE increases as you move right and up the table. (I added a picture)

[Melanie_Wong_1K]

Use the periodic table. Remember that right side and upper elements have higher ionization energies, so the upper right hand corner of the table has elements with the highest ionization energies and the lower left hand corner has the lowest. So if you're comparing two, say Sulfur and Fluorine, Sulfur would have a lower ionization energy and would act as the center element in a Lewis Dot Structure. Here are a few more examples:

Phosphorus or Nitrogen: Phosphorus is lower
Sulfur or Chlorine: Sulfur is lower
Potassium and Chlorine: Potassium is lower

[LeontyneHenderson2E]

Is the second ionization energy always more than the first for every atom?

[Tiffany Chen 3E]

Yes, the second ionization energy will always be more than the first for every atom because it will take more energy to remove the second electron, since before it is positively charged, making it easier to remove the electron. When it becomes neutral, it's harder to remove the electron.

[TiengTum2D]

Yes, the second ionization energy will always be more than the first for every atom because it will take more energy to remove the second electron, since before it is positively charged, making it easier to remove the electron. When it becomes neutral, it's harder to remove the electron.

Wait, did you mean the opposite? Before removing the first electron, the atom is neutral, making it easier to remove an electron. Once the first electron is removed, the atom is positively charged, making it that much harder to remove the 2nd one.

[Amy_Shao_2D]

Also, I remember in class Dr. Lavelle said hydrogen is never in the center.

[Hector_Gutierrez 1J]

Is the second ionization energy always more than the first for every atom?

The second ionization energy is always stronger because there will be a greater ratio of protons to electrons. During the first ionization of an element there is an equal number of protons and electrons. However, during the second ionization, there are more protons then electrons which means there is a stronger pull towards the center of an atom, thus making it more difficult to remove an electron.