Which anions have the largest and smallest radii? Thank you!!

The smallest anion probably is H^-. I'm not sure you can say what the largest anion (or cation) is since complex ions can carry a - or + charge and these can get large. It would be complicated to even try to calculate the diameter of those things. For example Fe(CN)63- or UO22+

To determine the anions with the largest and smallest radii, you need to consider the periodic trend of atomic size in the periodic table.

The atomic size generally decreases as you move from left to right across a period (horizontal row) of the periodic table, and it increases as you move down a group (vertical column). This trend is primarily due to the increasing number of protons and electrons in the nucleus, which leads to a stronger attraction and tighter hold on the outermost electrons.

Anions are formed when atoms gain electrons, resulting in an increased electron-electron repulsion and an expansion of the electron cloud. This expansion means that anions are generally larger than their corresponding neutral atoms.

Now, let's apply this information to determine the anion with the smallest and largest radii:

1. Smallest Anion: The smallest anion will be formed when an atom from the right side of the periodic table gains an electron. These elements have a relatively large number of protons, leading to a strong attractive force between the nucleus and the electrons. Therefore, the electron cloud is closely held, resulting in a small anion. Examples of small anions include fluoride (F-) and oxygen (O2-).

2. Largest Anion: The largest anion will be formed when an atom from the left side or the bottom of the periodic table gains an electron. These elements have a relatively low nuclear charge, which means weaker attraction to the added electron. Consequently, the electron cloud expands more, resulting in a larger anion. Examples of large anions include iodide (I-) and sulfide (S2-).

So, in summary, the anions with the largest radii are typically found in the lower-left region of the periodic table (e.g., iodide or sulfide), while the anions with the smallest radii are generally formed from elements in the upper-right region of the periodic table (e.g., fluoride or oxygen).

Remember, this explanation is based on general trends, and there may be exceptions in specific elements or cases.