The outer electronic configuration of alkaline earth metals is

Options

A. `ns^2`
B. `ns^1`
C. `np^6`
D. `nd^10`

Explanation

To determine the outer electronic configuration of alkaline earth metals, we will follow these steps:

### Step 1: Identify the Alkaline Earth Metals
The alkaline earth metals are located in Group 2 of the periodic table. The elements in this group are:
- Beryllium (Be)
- Magnesium (Mg)
- Calcium (Ca)
- Strontium (Sr)
- Barium (Ba)
- Radium (Ra)

### Step 2: Determine the Atomic Numbers
Next, we need to know the atomic numbers of these elements:
- Beryllium (Be) - Atomic number 4
- Magnesium (Mg) - Atomic number 12
- Calcium (Ca) - Atomic number 20
- Strontium (Sr) - Atomic number 38
- Barium (Ba) - Atomic number 56
- Radium (Ra) - Atomic number 88

### Step 3: Write the Electronic Configurations
Now, we will write the full electronic configurations for each of these elements:
- **Beryllium (Be)**: Atomic number 4 → 1s² 2s²
- **Magnesium (Mg)**: Atomic number 12 → 1s² 2s² 2p⁶ 3s²
- **Calcium (Ca)**: Atomic number 20 → 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
- **Strontium (Sr)**: Atomic number 38 → 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s²
- **Barium (Ba)**: Atomic number 56 → 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s²
- **Radium (Ra)**: Atomic number 88 → 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s²

### Step 4: Identify the Outer Electronic Configuration
From the configurations above, we can see that the outermost shell (the highest principal quantum number, n) for all alkaline earth metals has the configuration of ns², where n varies based on the element:
- For Be: n = 2 → 2s²
- For Mg: n = 3 → 3s²
- For Ca: n = 4 → 4s²
- For Sr: n = 5 → 5s²
- For Ba: n = 6 → 6s²
- For Ra: n = 7 → 7s²

### Final Answer
Thus, the outer electronic configuration of alkaline earth metals can be generalized as **ns²**, where n is the principal quantum number that varies from 2 to 7 for these elements.

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