The group of elements with the smallest atomic radii is the noble gases, specifically those in the helium group (Group 18). These elements, such as helium and neon, have very low atomic radii due to their high effective nuclear charge and complete electron shells, which pull the electrons closer to the nucleus. As you move across a period in the Periodic Table from left to right, atomic radii generally decrease, with noble gases being some of the smallest.
As we descend down the group, the atomic radii increases. This is because the number of shells increases.
I think that the ionic radii decrease
group 1 elements
The atomic radii of members of the Group 1A (Alkali metals), increases down the group. Therefore Francium has the largest atomic radius of the Alkali metals. However Fr has no stable isotopes, thus is not naturally occurring. So Cs-133 is the largest you can find.
The atomic radii of main-group elements generally increase down a group. This is because as you move down a group, the principal quantum number increases, leading to larger atomic orbitals and a greater distance between the nucleus and the outermost electron, resulting in a larger atomic radius.
The group of elements with members of the smallest atomic radii for a given period is the group of noble gases. Noble gases have the smallest atomic radii because they have a completely filled valence shell, which results in strong electron-electron repulsions and a smaller atomic size.
Atoms with the smallest radii in the alkaline-earth group are found at the top of the group, such as beryllium. This is because as you move down the group, additional electron shells are added, increasing the atomic radius.
The elements with the smallest atomic radii are found in the top of the P block of the periodic table. Helium (He) has the smallest atomic radius. Francium, on the other side of the periodic table (very bottom of the S block), has the largest atomic radius.
A hydrogen atom has the smallest radii.
they are most reactive
As we descend down the group, the atomic radii increases. This is because the number of shells increases.
I think that the ionic radii decrease
group 1 elements
The radii of elements generally decrease as you move from left to right across a period in the periodic table. The radii then increase as you move down a group in the periodic table. This trend is due to changes in the atomic structure of the elements.
Group 18 (Noble Gases) contains the largest main group elements because they have the highest atomic numbers and largest atomic radii among the main group elements.
Shielding.
Atomic radii become larger as you go from top to bottom of the periodic chart, but they get smaller as you go from left to right. Therefore, the elements with the smallest radii are in the upper right hand corner. Of S, Al, Na, and Ba, sulfur is the closest to the upper right corner and has the smallest radius of those elements.