Amongst the following elements which has the largest atomic size ?

Options

A. magnesium
B. phosphours
C. silicon
D. chlorine

Answer

To determine which element has the largest atomic size among a given set of elements, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements**: First, we need to know which elements we are comparing. For this example, let's assume we are comparing elements from the third period of the periodic table: Sodium (Na), Magnesium (Mg), and Chlorine (Cl).

2. **Locate the Elements in the Periodic Table**:
- Sodium (Na) is in Group 1, Period 3.
- Magnesium (Mg) is in Group 2, Period 3.
- Chlorine (Cl) is in Group 17, Period 3.

3. **Understand Atomic Size Trends**:
- Atomic size generally decreases across a period from left to right. This is because as we move from left to right, the number of protons in the nucleus increases, which increases the effective nuclear charge (Z effective).
- A higher Z effective pulls the electrons closer to the nucleus, resulting in a smaller atomic size.

4. **Compare the Elements**:
- Since Sodium (Na) is on the left side of the period, it will have the largest atomic size among these three elements.
- Magnesium (Mg) will be smaller than Sodium (Na) but larger than Chlorine (Cl).
- Chlorine (Cl), being further to the right, will have the smallest atomic size.

5. **Conclusion**: Therefore, among Sodium (Na), Magnesium (Mg), and Chlorine (Cl), Sodium (Na) has the largest atomic size.

### Final Answer:
**Sodium (Na) has the largest atomic size among the given elements.**

---