Comparing Atomic Radii: K+ vs Ar

[rdgt3000]

which atom has a larger atomic radius: K+ or Ar ?

 

[mrjeffy321]

Both have the same number of electrons, but think about the number of protons in the nucleus of the K+ ion and in the Argon atom. How will the number of protons affect the atomic (or ionic) radius? Think of the general periodic trend of atomic radii when the outermost shell is the same but atomic number is increasing.

 

[Blueshift5]

In general, atoms with more protons in their nucleus tend to have smaller atomic radii due to increased nuclear charge. Therefore, based on their atomic structures, it can be predicted that Ar, with 18 protons, will have a smaller atomic radius than K+, with 19 protons. This is because the additional proton in K+ will increase its nuclear charge, pulling the electrons closer to the nucleus and decreasing its atomic radius. Additionally, K+ has lost an electron compared to the neutral atom K, further decreasing its atomic radius. Therefore, K+ has a smaller atomic radius than Ar. However, it is important to note that other factors such as electron configuration and atomic bonding can also affect atomic radii and further research would need to be done for a more precise comparison.