To determine which element forms the ion with the largest ionic radius, let’s first understand the key concepts involved:
1. Ionic Radius: The radius of an atom's ion.
2. Formation of Ions: Atoms form ions by gaining or losing electrons.
- Cations (positive ions) are formed by the loss of electrons and generally have a smaller radius than the neutral atom.
- Anions (negative ions) are formed by the gain of electrons and generally have a larger radius than the neutral atom.
3. Trends in the Periodic Table:
- Moving down a group, ionic radius increases because additional electron shells are added, making the ions larger.
- Moving across a period from left to right, cations typically decrease in size due to increased nuclear charge without additional shielding, drawing electrons closer to the nucleus. Anions also become smaller across a period but not as significantly as cations.
4. Evaluation of the Elements in the Table:
- Considering only the given elements: [tex]\( Rb, Sr, In, Sn, Sb, Te, I, Xe, Cs, Ba, Th, Pb, Bi, Po \)[/tex]
5. Finding the Largest Ionic Radius:
- The element forming the ion with the largest ionic radius will be the one that:
- Forms a cation and is located further down its respective group (increased number of electron shells).
- Largest atomic number within its group.
Considering these points, the largest ionic radius will be associated with elements forming negative ions that are further down the group due to additional electron shells and decreased effective nuclear charge per electron.
From the options given, [tex]\( F_r \)[/tex] (Francium) will form the ion with the largest ionic radius. This is because it is located in the furthest down group 1 and thus has the largest addition in shell numbers, contributing to the largest size for its cation [tex]\( F_r^+ \)[/tex].
Therefore, Francium ([tex]\( F_r \)[/tex]) forms the ion with the largest ionic radius in its cationic form [tex]\( F_r^+ \)[/tex].
