Atomic Radius

[Cecilia Cisneros 1F]

How do we know between ions of the same element, which ion may have a larger atomic radius?

Fe2+ vs. Fe3+

Also, do isoelectronic elements have the same size radius? I know they have the same number of electrons, but I am not sure if they have the same atomic radius.

[Rich Luong 1D]

The ion with the larger atomic radius would be the one with the less positive charge. In this case, it would be Fe 2+. The reason being is that the one with the lesser positive charge has more electron repulsion between the electrons which result in the radius to be slightly expanded. For the more positive charge, there is less of the repulsion allowing for the electrons to be more easily attracted to the nucleus thus decreasing the atomic radius. For isoelectronic elements, the atomic radius varies. Although the isoelectronic elements have the same number of electrons, the number of protons varies. So essentially, the elements that have more protons and less electron repulsion would have the smallest atomic radius. I hope this helps!

[Cecilia Cisneros 1F]

The ion with the larger atomic radius would be the one with the less positive charge. In this case, it would be Fe 2+. The reason being is that the one with the lesser positive charge has more electron repulsion between the electrons which result in the radius to be slightly expanded. For the more positive charge, there is less of the repulsion allowing for the electrons to be more easily attracted to the nucleus thus decreasing the atomic radius. For isoelectronic elements, the atomic radius varies. Although the isoelectronic elements have the same number of electrons, the number of protons varies. So essentially, the elements that have more protons and less electron repulsion would have the smallest atomic radius. I hope this helps!

WOW thank you so much that cleared it up so much for me!!!

[Sharon Kim 2A]

We know if the ions have a larger radius is they have a less positive charge. If they have a high positive charge then that means the ion lost electrons and electrons is a key part that makes the size of ions and atoms because of repulsion. Which is the electron cloud.

[Muskaan Abdul-Sattar]

The ion with the larger radius would be the ion that has a less positive charge, in this case, Fe2+.

[Neel Sharma 3F]

The larger the cation's charge the smaller the atomic radius as the loss of electrons reduces the size of the orbitals and increases the effective nuclear charge which pulls the electrons closer to the nucleus as a result. Hope this helps!

[Melanie Krahn 1C]

If the ion has a larger radius, it will also have a less positive charge. If it has a high positive charge then that indicates that the ion has lost some electrons. Electrons play an important part, making up the size of atoms and ions because of the repulsion they cause in the electron cloud.

[Juliana Rosales 1H]

I think it should be Fe2

[205323697]

how do we use the atomic radius to calculate the bond length? what information would we need to know?

[Trisha Badjatia 2L]

how do we use the atomic radius to calculate the bond length? what information would we need to know?

I think you need to actually know the covalent radii to calculate the bond length. Atomic radius is merely for a singular atom.

[Sally_Luo_3F]

The ion with the less positive charge would have a greater atomic radius. In this case, it would be Fe2+.

[Fiona H 2E]

Less positively charged ions tend to have a larger radius, so FE 2+ is the correct answer here.

[masontsang]

Hi!

Since Fe2+ has a lower effective nuclear charge than Fe3+, Fe2+ should have a bigger radius. Ions with lower effective nuclear charges tend to have bigger radii while ions with higher effective nuclear charges tend to have smaller radii. Effective nuclear charge is determined by the number of protons and electrons that an atom or ion has. Since Fe2+ has a lower effective nuclear charge, electrons aren't pulled in as close to the nucleus (in comparison to Fe3+), so it should have a larger radius.

I hope this helps!

[Olivia D 3B]

A general trend on the periodic table that I have found to be helpful conceptually for problems involving atomic radius is that atomic radius increases going vertically down the period table (from the top to the bottom) and atomic radius decreases going horizontally across the periodic table from the left to the right.