Sodium ion is isoelectronic with……..atom

Options

A. `Mg^(2+)`
B. `Al^(3+)`
C. Ne
D. `N^(3-)`

Answer

To determine which atom is isoelectronic with the sodium ion (Na⁺), we need to follow these steps:

### Step 1: Determine the Atomic Number of Sodium
The atomic number of sodium (Na) is 11.

### Step 2: Find the Electron Configuration of Sodium
The electron configuration of sodium (Na) is:
- 1s² 2s² 2p⁶ 3s¹

### Step 3: Determine the Electron Configuration of Sodium Ion (Na⁺)
When sodium loses one electron to form Na⁺, its electron configuration becomes:
- 1s² 2s² 2p⁶
This means Na⁺ has a total of 10 electrons.

### Step 4: Identify Other Atoms/Ions with 10 Electrons
We need to find other atoms or ions that also have 10 electrons. We can check the following:

1. **Magnesium Ion (Mg²⁺)**:
- Atomic number of magnesium (Mg) is 12.
- Electron configuration of Mg is 1s² 2s² 2p⁶ 3s².
- When it loses two electrons (Mg²⁺), its configuration becomes 1s² 2s² 2p⁶ (10 electrons).

2. **Aluminum Ion (Al³⁺)**:
- Atomic number of aluminum (Al) is 13.
- Electron configuration of Al is 1s² 2s² 2p⁶ 3s² 3p¹.
- When it loses three electrons (Al³⁺), its configuration becomes 1s² 2s² 2p⁶ (10 electrons).

3. **Neon (Ne)**:
- Atomic number of neon (Ne) is 10.
- Electron configuration of Ne is 1s² 2s² 2p⁶ (10 electrons).

4. **Nitride Ion (N³⁻)**:
- Atomic number of nitrogen (N) is 7.
- Electron configuration of N is 1s² 2s² 2p³.
- When it gains three electrons (N³⁻), its configuration becomes 1s² 2s² 2p⁶ (10 electrons).

### Step 5: Conclusion
All the following species are isoelectronic with Na⁺:
- Mg²⁺
- Al³⁺
- Ne
- N³⁻

Thus, sodium ion (Na⁺) is isoelectronic with magnesium ion (Mg²⁺), aluminum ion (Al³⁺), neon (Ne), and nitride ion (N³⁻).