The Question is from neet-chemistry classification-of-elements-and-periodicity-in-prop , and it was created by the author Mr. S M HUSSAIN

Question

Which factor has the LEAST significant influence on the atomic radius of an element?

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Atomic Structure and Periodic Trends
 **Related Topics**: Effective nuclear charge, shielding effect, electron shells, isotopes
 **Prerequisites**: Understanding of electron configuration, nuclear forces, and Coulomb's law.
## SOLUTION PATHWAY
**Given Information**:
The question asks to identify the factor with the least influence on atomic radius.
**Method & Steps**:
1. **Analyze the influence of each factor:**
    * **Effective nuclear charge ($Z_{eff}$):**  This is the net positive charge experienced by the outermost electrons. A higher $Z_{eff}$ attracts the valence electrons more strongly, leading to a smaller atomic radius.  $Z_{eff} = Z - S$, where Z is the atomic number and S is the shielding constant.
    * **Number of electron shells:**  Adding electron shells increases the distance between the nucleus and the outermost electrons, thus increasing the atomic radius.
    * **Number of neutrons in the nucleus:** Neutrons do not directly participate in the electrostatic interactions between the nucleus and electrons. They primarily affect the mass of the atom but have minimal influence on the size of the electron cloud. Isotopes, which differ in the number of neutrons, have essentially the same atomic radius.
    * **Shielding effect of inner electrons:** Inner electrons shield the outer electrons from the full positive charge of the nucleus, reducing the effective nuclear charge experienced by the outer electrons. Increased shielding leads to a larger atomic radius.
2. **Compare the relative influences:**
    The effective nuclear charge, number of electron shells, and shielding effect all significantly affect the atomic radius.  However, the number of neutrons has a negligible effect.
3. **Identify the least significant factor:**
    The number of neutrons has the least influence on the atomic radius.
**Result**: The number of neutrons in the nucleus has the least significant influence on the atomic radius.
**Verification**:  Isotopes, which differ only in the number of neutrons, have virtually identical atomic radii, confirming that the number of neutrons is not a major determining factor.
## OPTION ANALYSIS
A :x: The effective nuclear charge significantly affects atomic radius.
B :x: The number of electron shells significantly affects atomic radius.
C ✓: The number of neutrons has a negligible effect on atomic radius.
D :x: The shielding effect significantly affects atomic radius.
## LEARNING AIDS
 **Common Mistakes**:
  1. Confusing atomic number with atomic mass: Atomic number determines the number of protons and electrons, significantly impacting the atomic radius. Atomic mass includes neutrons and is less relevant for radius.
  2. Overlooking the shielding effect:  The shielding effect is a crucial factor in determining the effective nuclear charge and thus the atomic radius.
 **Quick Tips**:
  1. Remember that isotopes have almost identical atomic radii, highlighting the minor role of neutrons.
  2. Focus on the electrostatic interactions between the nucleus and the outermost electrons when considering atomic radius.

Mr. S M HUSSAIN · Answer

The effective nuclear charge

Mr. S M HUSSAIN · Answer

The number of electron shells

Mr. S M HUSSAIN · Answer

The correct Option is "The number of neutrons in the nucleus"

Mr. S M HUSSAIN · Answer

The shielding effect of inner electrons

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