Question Video: Determining the Group of an Element Based on Its Successive Ionization Energies Chemistry

Given the data of successive ionization energies (in kJ/mol) in the table shown, which of the following elements is most likely to be in group III of the periodic table? [A] Element 1 [B] Element 2 [C] Element 3 [D] Element 4 [E] Element 5

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Video Transcript

Given the data of successive ionization energies in kilojoules per mole in the table shown, which of the following elements is most likely to be in group three of the periodic table?

The table provides the successive ionization energies of five unknown elements from the first ionization energy to the sixth. Successive ionization energies are values that quantify how much energy is needed to consecutively remove electrons from one gaseous state element. A specific element’s pattern of consecutive ionization energies provides insight to the electronic configuration of its atoms.

Generally, ionization energy increases as more electrons are removed. Removing electrons from positively charged ions requires more energy. However, large increases in ionization energy that are significantly different from the general increase indicate that electrons are being removed from an energy level closer to the nucleus. Electrons closer to the nucleus are more tightly bound by the electrostatic attraction, so more energy is required to remove them.

Let’s have a look at the patterns of each of the five unknown elements to uncover their electronic configurations and determine which could be in group three of the periodic table. Element one has the most significant increase in ionization energy between the fourth and fifth ionization energies. This indicates that the first four electrons removed were likely in the same energy level and were more loosely bound than the fifth. The fifth electron removed was likely in an energy level closer to the nucleus than the first four electrons. Therefore, it is likely that element one has four valence electrons and can be found in group four of the periodic table, which we might also call group 14, depending if we count the d-block transition metals.

Element two shows the most significant increase between the first and second ionization energies. Therefore, it is likely that element two is in group one of the periodic table. Element three has the most significant increase between the second and third ionization energies. It is likely that element three is in group two of the periodic table. Element four has the largest increase between the third and fourth ionization energies. It is likely that element four is in group three or 13 of the periodic table. Finally, element five has no increases that are significantly different from the rest and, thus, could be in group 16, 17, or 18.

Therefore, the element that is most likely to be in group three of the periodic table is element four.

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