Arrange the following particles from smallest to largest.
f, f^-1, br, br^-1

F, F⁻¹, Br, Br⁻¹

Explanation:

Atomic radii:

It is the inter nuclear distance between bonded atom.

Trend along group:

When we move from top to bottom in a group atomic size increases with increase of atomic number because of addition of electron in next energy level. Thus nuclear attraction becomes weaker on valence electrons and size gets increased. Moreover shielding effect also protect the valance electrons from nuclear attraction.

when we move from bottom to top the atomic size decreases because of decrease in atomic number and energy level.

For example

In halogens the fluorine has smaller size than rest of halogens elements because it is present in top of this column. while bromine is present third to the fluorine that's why its atomic size is larger than fluorine. When an extra electron is added the atomic size becomes greater than neutral atom because of addition of electron to the next energy level. That's why anionic size is greater than neutral atom.

The given particles thus arranged in smallest to largest size in following order.

F, F⁻¹, Br, Br⁻¹