[positiveion]

The first four ionization energies (kj mol^-1) for a particular element are 550, 1064, 4210 and 5500 respectively. This element shoudl be placed in the same group as:
Li/Be/B/C

The answer says that it is B, but I don't understand why. I would have thought that it was Be.


Another question:
Which of the following elements has the lowest first ionization energy?
Li/Mg/Na/Al

The answer is Na which I agree with, but I feel like it contradicts the answer to the first question.

As can be seen from this graph:

After one electron is removed from B (2 points in front of Li), it becomes Be (1 point in front of Li)
After a second electron is removed, it becomes Li
After a third electron is removed, it becomes He

I really don't get it. Li has a really low first ionization energy and that is the third and last elecron removed from B. It doesn't make sense for there to be a huge difference in ionization energy for the 2nd and 3rd ionization energy of B. It only makes sense if it was Be, since the difference between energies of the removal of electrons from Li and from He would be huge.

Am I right? Is the answer in the book wrong?

[UG]

I agree. Are you sure it wasn't like A) Li B) Be C) B D) C and the answer was B as in Be? 

[positiveion]

Great thanks.

And yeah and I'm sure.

It was actually a. Li b. Be c. B and d. C and the answer was c.

[cliverlong]

I think you mixing up

Trend in first ionization energy across a period http://www.chemguide.co.uk/atoms/properties/ies.html

Successive ionization energies for a single element: http://www.chemguide.co.uk/atoms/properties/moreies.html#top

For a single element, look for the big jump in ionization energy and that is probably where you move from one orbit to the next inner orbit (example given is first 8 ionization energies of chlorine)

Clive

[Borek]

The first four ionization energies (kj mol^-1) for a particular element are 550, 1064, 4210 and 5500 respectively. This element shoudl be placed in the same group as:
Li/Be/B/C

The answer says that it is B, but I don't understand why. I would have thought that it was Be.

At first sight that would be my answer as well.

After one electron is removed from B (2 points in front of Li), it becomes Be (1 point in front of Li)
After a second electron is removed, it becomes Li
After a third electron is removed, it becomes He

Perhaps that just the wording, but your statements are very wrong.

After one electron is removed from B it becomes B⁺ - it has identical electron configuration as Be.
After second electron is removed from B it becomes B²⁺ - it has identical electron configuration as Li.
After third electron is removed from B it becomes B³⁺ - it has identical electron configuration as He.

Just becuse it has identical configuration doesn't mean it became other element - charge of nucleus has not changed.