Which one of the following has the largest atomic radius? a) lithium b) sodium c) potassium d) chlorine

Options

A. a)Lithium
B. b)Sodium
C. c)Potassium
D. d)Chlorine

Explanation

To determine which element has the largest atomic radius among lithium, sodium, potassium, and chlorine, we can follow these steps:

### Step 1: Understand Atomic Radius Trends
- The atomic radius of elements varies based on their position in the periodic table.
- As we move from left to right across a period, the atomic radius decreases due to the increase in nuclear charge (effective nuclear charge), which pulls the electrons closer to the nucleus.
- As we move down a group, the atomic radius increases because additional electron shells are added, which outweighs the effect of increased nuclear charge.

### Step 2: Identify the Group and Period of Each Element
- Lithium (Li) is in Group 1 and Period 2.
- Sodium (Na) is in Group 1 and Period 3.
- Potassium (K) is in Group 1 and Period 4.
- Chlorine (Cl) is in Group 17 and Period 3.

### Step 3: Compare the Elements
- Lithium has the smallest atomic radius because it is at the top of Group 1.
- Sodium has a larger atomic radius than lithium because it is one period lower.
- Chlorine, being in Group 17 and in the same period as sodium, has a smaller atomic radius than sodium due to the increased nuclear charge.
- Potassium has the largest atomic radius because it is further down in Group 1, meaning it has more electron shells than lithium and sodium.

### Conclusion
Based on the trends and comparisons:
- Lithium < Chlorine < Sodium < Potassium
- Therefore, potassium (K) has the largest atomic radius among the given options.

### Final Answer
The element with the largest atomic radius is **c) potassium**.

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