Bond length

[Maria Roman 1A]

How can you tell when an atom has a longer bond?

an example: F, F^2-, F^2+

[Brynne Keyser 1B]

You can look at the number of electrons that are present in each molecule. If there are more lone pairs, they will repel each other and cause a longer bond to be formed.

[Paywand Baghal]

You can look at the number of electrons that are present in each molecule. If there are more lone pairs, they will repel each other and cause a longer bond to be formed.

So for F when more electrons are added, it makes the bond longer?

[Ignacio Ramirez 1J]

Draw the Lewis structure, look up the chart below for the radii for the corresponding bond, and find the sum of the two radii. Because the bond length is proportional to the atomic radius, the bond length trends in the periodic table follow the same trends as atomic radii: bond length decreases across a period and increases down a group.

[Aryana Nazem 1A]

You can look at the number of electrons that are present in each molecule. If there are more lone pairs, they will repel each other and cause a longer bond to be formed.

So for F when more electrons are added, it makes the bond longer?

Yes in this case because you are adding more electrons and therefore a lone pair

[Yitzchak Jacobson 1F]

I believe you can tell which atom has a longer bond length by looking at how many electrons are present within the atoms.
I hope this answers your question :)