Trends in Ionization Energies and Atom Size in Group 11a



If you look at a periodic table, you’ll see that the second column starting at the left is labeled group IIA so we’re going to take a look at the trends in ionization energies and atom size in this group. Right here is a list of elements in that group and so this right here is the second column of the periodic table. Now atom size goes from least to greatest in this column so we start out with beryllium which is the smallest element in this column and then we work our way down to radium which is the largest element in this group. Now, ionization energy works the other way. Ionization energy starts small at the bottom and works itself up to get bigger and bigger and so ionization energy is the amount of energy that it takes to remove an electron from an atom or molecule and so radium here has the lowest ionization energy and beryllium has the largest ionization energy so if you’re trying to take an electron from an element, it’s going to be easiest or easier to pull one from radium than it is from beryllium. Now we have something called first ionization energy and second ionization energy and so on and what that is is the first ionization energy is the amount of energy that it takes to take away the first electron from a parent atom and then you get to second ionization energy which is the amount of energy that it takes to remove the second electron from this ion and so you go on and on and on and so with all these elements the first ionization energy is less than the second ionization energy which is less than the third ionization energy. In addition to that fact right there the ionization decreases as the atom size increases which you may have already noticed because as size decreases or as size increases, ionization energy is decreasing as you move down this column and so because of that fact and this fact right here we have two conclusions and so first off, the first and second ionization energy is lower than the third and so these metals make ions with a plus 2 charge and so use this first and second ionization energy are lower than the third and so these metals are going to make ions with a plus 2 charge. The second conclusion from these trends is it is easier to remove the first two electrons from radium because it is a larger atom than it is to remove them from beryllium. So like I was saying beryllium has a much lower ionization energy than radium. Radium is a much larger atom and so larger atoms have lower ionization energies and so larger atoms give up electrons more easily than smaller atoms do. So that’s a look at the trends in ionization energies and atom size in group IIA.

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Last updated: 07/25/2017
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