Which element's atomic radius changes the most in size when it becomes ionized?

A. Fluorine
B. Lithium
C. Sodium
D. Chlorine

What do you mean by "most"? That's a relative term. Do you want the most in absolute terms or in percent?

like which one changes the most in size.

the answer is D

To determine which element's atomic radius changes the most when it becomes ionized, we need to consider the trend in atomic size across the periodic table.

The general trend for atomic radius moving from left to right across a period is that it decreases. This is due to an increase in the effective nuclear charge, which attracts the electrons more strongly, resulting in a smaller atomic size.

Now, let's analyze each option:

A. Fluorine is located on the right side of the periodic table, so if it loses an electron to become a cation, its atomic radius will decrease. However, since it is already a small atom, the change in size may not be as significant compared to other options.

B. Lithium is located in the first group (Group 1) on the far-left side of the periodic table. When it loses an electron to become a cation, its atomic radius will decrease. Since it is a larger atom to begin with, this change in size will likely be more noticeable.

C. Sodium is also located in the first group (Group 1) but is one period below lithium. When it loses an electron to form a cation, its atomic radius will decrease. However, sodium is larger than lithium to start with, so the change in size might not be as prominent.

D. Chlorine is located on the right side of the periodic table. If it gains an electron to become an anion, its atomic radius will increase. Since it is already a small atom, the change in size will likely be noticeable.

Considering the trends and the options given, the element that has the greatest change in atomic radius when ionized is most likely B. Lithium.