Which one of the following has the smallest atomic radius?

Options

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

Explanation

To determine which of the given elements has the smallest atomic radius, we can follow these steps:

### Step 1: Identify the Elements
We have the following elements to consider:
- Lithium (Li)
- Fluorine (F)
- Chlorine (Cl)
- Potassium (K)

### Step 2: Understand the Periodic Trends
We need to recall the periodic trends regarding atomic radius:
- Atomic radius **decreases** as you move from **left to right** across a period. This is due to the increasing nuclear charge, which pulls the electrons closer to the nucleus.
- Atomic radius **increases** as you move **down a group**. This is because additional electron shells are added, making the atom larger.

### Step 3: Locate the Elements on the Periodic Table
- Lithium (Li) is in Group 1 (alkali metals) and Period 2.
- Fluorine (F) is in Group 17 (halogens) and Period 2.
- Chlorine (Cl) is in Group 17 (halogens) and Period 3.
- Potassium (K) is in Group 1 (alkali metals) and Period 4.

### Step 4: Compare Atomic Radii
- Between Li and F (both in Period 2), F will have a smaller atomic radius than Li because F is further to the right in the same period.
- Cl is below F in Group 17, so Cl will have a larger atomic radius than F due to the addition of another electron shell.
- K is in Group 1 and is further down the periodic table than both Li and F, so K will also have a larger atomic radius than F.

### Step 5: Conclusion
From the comparison:
- Li > F (Li has a larger radius than F)
- Cl > F (Cl has a larger radius than F)
- K > F (K has a larger radius than F)

Thus, **Fluorine (F)** has the smallest atomic radius among the given elements.

### Final Answer
**Fluorine (F)** has the smallest atomic radius.

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