Metallic radii of some transitions element are given below. Which of these elements will have highest density ?
`{:("Element",Fe,Co,Ni,Cu),("Metallic",126,125,125,128),("radii/pm",,,,):}`

Options

A. Fe
B. Ni
C. Co
D. Cu

Explanation

To determine which of the given transition elements (Fe, Co, Ni, Cu) has the highest density, we can follow these steps:

### Step 1: Understand the Concept of Density
Density is defined as mass per unit volume. The formula for density (D) is:
\[ D = \frac{m}{V} \]
where \( m \) is the mass and \( V \) is the volume.

### Step 2: Analyze the Given Data
We have the following data for the metallic radii of the elements:
- Iron (Fe): 126 pm
- Cobalt (Co): 125 pm
- Nickel (Ni): 125 pm
- Copper (Cu): 128 pm

### Step 3: Identify Trends in the Periodic Table
As we move from left to right across a period in the periodic table:
- The atomic mass generally increases.
- The metallic radius generally decreases due to an increase in effective nuclear charge.

### Step 4: Relate Atomic Mass and Volume to Density
Since density increases with increasing mass and decreasing volume, we can conclude that:
- As we move from Fe to Cu, the atomic mass increases while the radius (and thus volume) decreases.

### Step 5: Compare the Elements
- Iron (Fe) has a lower atomic mass than Cobalt (Co), Nickel (Ni), and Copper (Cu).
- Cobalt (Co) has a lower atomic mass than Nickel (Ni) and Copper (Cu).
- Nickel (Ni) has a lower atomic mass than Copper (Cu).

### Step 6: Determine the Element with the Highest Density
Since density increases as we move from left to right in the periodic table, and given that Copper (Cu) is the last element in the series, it will have the highest density among the four elements.

### Conclusion
Thus, Copper (Cu) has the highest density among the given transition elements.

### Final Answer
**Copper (Cu) has the highest density.**

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