Final answer:
Atomic radii decrease from left to right across a periodic table row and increase from top to bottom down a column, resulting in the largest atoms in the lower left and smallest in the upper right corner.OPTION 1
Step-by-step explanation:
Atomic radii tend to decrease from left to right across a row in the periodic table due to increasing nuclear charge which pulls the electron shells closer to the nucleus. Conversely, atomic radii increase down a column as the number of electron shells increases, and thus the outermost electrons are located further from the nucleus. This is also due to the electron shell acquiring a higher principal quantum number, which translates to a larger size for these orbitals. As a result, the largest atoms are located in the lower left corner of the periodic table, and the smallest in the upper right corner, following the clear periodic trend based on atomic number.
The atomic radii tend to increase as you go down a group and decrease as you go across a period.
As you move down a group, the atomic radius increases because the valence electron shell is getting larger and lies physically farther away from the nucleus. On the other hand, as you go across a period, the atomic radius decreases because the effective nuclear charge felt by the electrons increases and the repulsions between electrons in the same principal shell decrease.
For example, in Figure 9.9.1, you can see that the atomic radii generally become smaller as you go across the periodic table and larger as you go down any one column.