How many unpaired electrons are there in Ni element ?

Explanation

To determine the number of unpaired electrons in the nickel (Ni) element, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Nickel:**
- The atomic number (Z) of nickel (Ni) is 28.

2. **Write the Electronic Configuration:**
- The electronic configuration of nickel can be written as:
\[ \text{Ni: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^8 \, 4s^2 \]

3. **Analyze the d-Orbital:**
- The d-orbital can hold a maximum of 10 electrons. In the case of nickel, the 3d subshell has 8 electrons (3d^8).

4. **Draw the d-Orbital Filling:**
- When filling the d-orbitals, we follow Hund's rule, which states that electrons will fill degenerate orbitals singly before pairing up. The filling of the 3d orbitals with 8 electrons can be visualized as follows:
- Each of the five d-orbitals can hold 2 electrons.
- The filling would look like this:
- ↑↓ (1st orbital)
- ↑↓ (2nd orbital)
- ↑ (3rd orbital)
- ↑ (4th orbital)
- (5th orbital remains empty)
- This results in 2 paired electrons in the first two orbitals and 2 unpaired electrons in the last two orbitals.

5. **Count the Unpaired Electrons:**
- From the filling of the 3d orbitals, we can see that there are **2 unpaired electrons**.

### Final Answer:
- The number of unpaired electrons in nickel (Ni) is **2**.