Which transition metal has lowest density?

Options

A. Sc
B. Ti
C. Zn
D. La

Answer

To determine which transition metal has the lowest density, we can analyze the electronic configurations and the number of unpaired electrons in the valence shell of various transition metals.

### Step-by-Step Solution:

1. **Understanding Density in Transition Metals**:
- Density in transition metals is influenced by the number of unpaired electrons available for bonding. More unpaired electrons generally lead to stronger metallic bonding, which can increase density.

2. **Analyzing Scandium (Sc)**:
- Electronic configuration: Argon (Ar) 3d¹ 4s².
- Number of unpaired electrons: 1 (the 3d subshell has 1 unpaired electron).
- Scandium has low density due to having only one unpaired electron available for bonding.

3. **Analyzing Titanium (Ti)**:
- Electronic configuration: Argon (Ar) 3d² 4s².
- Number of unpaired electrons: 2 (the 3d subshell has 2 unpaired electrons).
- Titanium has a higher density than scandium due to having more unpaired electrons.

4. **Analyzing Zinc (Zn)**:
- Electronic configuration: Argon (Ar) 3d¹⁰ 4s².
- Number of unpaired electrons: 0 (the 3d subshell is fully filled).
- Zinc has a normal density, as it does not contribute unpaired electrons for bonding.

5. **Analyzing Lanthanum (La)**:
- Electronic configuration: Xenon (Xe) 5d¹ 6s².
- Number of unpaired electrons: 3 (1 from the 5d and 2 from the 6s).
- Lanthanum has a good density due to having multiple unpaired electrons.

6. **Conclusion**:
- Among the analyzed transition metals, Scandium (Sc) has the lowest density due to having only one unpaired electron available for bonding.

### Final Answer:
The transition metal with the lowest density is **Scandium (Sc)**.

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