Answer:
138 pm (predicted)
Explanation:
The ionic radius is half the distance between atomic ions in a crystal lattice. To find the value, ions are treated as if they were hard spheres. The size of an element's ionic radius follows a predictable trend on the periodic table. As you move down a column or group, the ionic radius increases. Advanced calculations show that the radius of an tennessine atom that has formed one covalent bond would be 165 pm, while that of astatine would be 147 pm. With the seven outermost electrons removed, tennessine is finally smaller; 57 pm for tennessine and 61 pm for astatine.
