Question

introduction: the periodic table is so named because similar patterns repeat, or appear periodically throughout the table. these patterns are referred to as periodic trends. question: how do atomic radius, ionization energy, and electron affinity change throughout the periodic table? 1. predict: based on your investigations in activities a and b, predict where in the periodic table you will typically find the following: largest atoms, smallest atoms, highest ionization energy, lowest ionization energy, highest electron affinity, lowest electron affinity. 2. observe: choose atomic radius from the drop - down menu to see the relative sizes of the elements. in which parts of the table do you find the largest and smallest atoms? 3. observe: choose ionization energy. ionization energy is shown by color. in which parts of the table do you find atoms with the highest, and the lowest, ionization energies? 4. observe: choose electron affinity. electron affinity is shown by color, with darker blue corresponding to the highest (most negative) electron affinity. in which parts of the table do you find the greatest and lowest attraction for electrons? 5. infer: which group has high ionization energies but very weak electron affinities? which group has high ionization energies but very weak electron affinities? why do you think this is so?

Explanation:

1. Atomic radius: In the periodic table, atomic radius generally increases down a group and decreases across a period from left - to - right. So, the largest atoms are in the lower left region (more electron shells and less effective nuclear charge attraction) and the smallest atoms are in the upper right region (fewer electron shells and high effective nuclear charge).
2. Ionization energy: It is the energy required to remove an electron from an atom. Ionization energy increases across a period from left to right (due to increasing nuclear charge and decreasing atomic radius) and decreases down a group (due to increasing atomic size and shielding effect). So, the highest ionization energy is in the upper right region and the lowest is in the lower left region.
3. Electron affinity: It is the energy change when an electron is added to an atom. Electron affinity generally increases across a period from left to right (atoms are more electronegative and have a greater attraction for electrons). It is highest (most negative) in the upper right region and lowest in the lower left region.
4. For the group with high ionization energies but very weak electron affinities, the noble gases (Group 18) fit this description. They have a full outer - shell electron configuration, which makes them very stable. It is difficult to remove an electron (high ionization energy) and adding an electron would disrupt this stable configuration, so they have very low electron affinities.

Answer:

1. Largest atoms: Lower left region; Smallest atoms: Upper right region; Highest ionization energy: Upper right region; Lowest ionization energy: Lower left region; Highest electron affinity: Upper right region; Lowest electron affinity: Lower left region
2. Largest atoms are in the lower left region, smallest atoms are in the upper right region.
3. Highest ionization energy is in the upper right region, lowest ionization energy is in the lower left region.
4. Greatest electron affinity is in the upper right region, lowest electron affinity is in the lower left region.
5. Group 18 (noble gases) has high ionization energies but very weak electron affinities. Because they have a full outer - shell electron configuration, making them stable and resistant to electron addition or removal.