What is the atom Radius?

Let’s talk about the an interpretation of the atomic radius, also called atomic size, and the atomic radius trend top top the regular table. The atomic radius is measure as fifty percent the distance in between two nuclei the the very same atoms that space bonded together. While your initial believed may have been to measure the distance from the facility of one atom’s nucleus to the leaf of that electron cloud, this is inaccurate and not feasible. This is since the borders of orbitals are rather fuzzy, and they also readjust under different conditions. For this reason the atomic radius is measure as presented in the diagram below.

You are watching: An atom of which element has the largest atomic radius?


Atomic Radius tendency on the routine Table


Atomic radii boost toward the bottom left corner of the regular table, through Francium having the largest atomic radius. Atoms decrease in size across the duration and boost in size down the group. Let’s failure the trend into its duration and team trends.

Period Trends

There are numerous trends ~ above the regular table. For example, ionization energy, electronegativity, and of course atomic radius which we will discuss now. Across a period, atom radii decrease. This is since while the number of electrons boosts down the period, castle only add to the very same main power level, and therefore carry out not increase the electron cloud. Under the period, however, the variety of protons likewise increases. This boosted positive charge attracts or pulls, the electron in closer to the nucleus, to decrease the atomic radius.


One thing to note is the the impact of the attraction between the positively charged nucleus and the electron is slightly countered by the repulsion of electrons as they space successively added. This is why the distinction in atom radii decreases down each period.

Group Trend

Down a group, atomic radii increase. This is due to the fact that between each group, electrons occupy successively higher energy levels. As electron cloud size increase, so do atomic radii.


The trend on a Graph

As shown in the graph below, the atomic radius is largest at the first element in every period, and also it decreases down each period.

See more: Do Seventh Day Adventists Celebrate Halloween, Halloween And Seventh


Smallest and Largest atomic Radius

Francium has actually the biggest atomic size on the routine table, and also helium has actually the the smallest atomic size.