Which one of the following has the largest atomic radius?

Options

A. Li
B. F
C. K
D. Br

Explanation

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

### Step 1: Identify the Elements
First, we need to identify the elements provided in the options. Let's assume the options are:
1. Lithium (Li)
2. Potassium (K)
3. Fluorine (F)
4. Bromine (Br)

### Step 2: Understand the Periodic Table Arrangement
Next, we arrange these elements based on their position in the periodic table:
- Lithium (Li) and Potassium (K) are in Group 1 (Alkali Metals).
- Fluorine (F) and Bromine (Br) are in Group 17 (Halogens).

### Step 3: Analyze Atomic Radius Trends
Now, we need to analyze the trends of atomic radius:
- **Across a Period**: As we move from left to right across a period, the atomic radius decreases. This is due to the increase in nuclear charge, which pulls the electrons closer to the nucleus.
- **Down a Group**: As we move down a group, the atomic radius increases. This is because additional electron shells are added, which increases the distance between the nucleus and the outermost electrons, leading to a larger atomic size.

### Step 4: Compare the Elements
Now, we can compare the atomic radius of the elements:
- Between Lithium (Li) and Potassium (K), Potassium is lower in the group, so it has a larger atomic radius than Lithium.
- Between Fluorine (F) and Bromine (Br), Bromine is lower in the group, so it has a larger atomic radius than Fluorine.
- However, both Potassium (K) and Bromine (Br) are in different groups. Potassium is in Group 1 and is lower down, while Bromine is in Group 17 and is higher up.

### Step 5: Conclusion
Since Potassium (K) is an alkali metal and is located lower in the periodic table compared to the halogens, it will have the largest atomic radius among the four elements provided.

### Final Answer
The element with the largest atomic radius is **Potassium (K)**.

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