Find the total number of elements out of the given elements which will need two more electrons to achieve 8 electrons in the outermost shell.
Na, C, N, P, F, O 

Answer

To find the total number of elements from the given list that need two more electrons to achieve 8 electrons in their outermost shell, we will analyze the electron configurations of each element.

### Step-by-Step Solution:

1. **Identify the Elements and Their Electron Configurations**:
- Sodium (Na): 1s² 2s² 2p⁶ 3s¹
- Carbon (C): 1s² 2s² 2p²
- Nitrogen (N): 1s² 2s² 2p³
- Phosphorus (P): 1s² 2s² 2p⁶ 3s² 3p³
- Fluorine (F): 1s² 2s² 2p⁵
- Oxygen (O): 1s² 2s² 2p⁴

2. **Determine the Number of Electrons Needed for Each Element to Achieve an Octet**:
- **Sodium (Na)**: Has 1 electron in the outermost shell (3s¹). Needs 1 electron to achieve an octet.
- **Carbon (C)**: Has 4 electrons in the outermost shell (2s² 2p²). Needs 4 electrons to achieve an octet.
- **Nitrogen (N)**: Has 5 electrons in the outermost shell (2s² 2p³). Needs 3 electrons to achieve an octet.
- **Phosphorus (P)**: Has 5 electrons in the outermost shell (3s² 3p³). Needs 3 electrons to achieve an octet.
- **Fluorine (F)**: Has 7 electrons in the outermost shell (2s² 2p⁵). Needs 1 electron to achieve an octet.
- **Oxygen (O)**: Has 6 electrons in the outermost shell (2s² 2p⁴). Needs 2 electrons to achieve an octet.

3. **Count the Elements that Need Two More Electrons**:
- From the analysis above, only **Oxygen (O)** needs 2 more electrons to complete its octet.

4. **Conclusion**:
- The total number of elements from the given list that need two more electrons to achieve 8 electrons in their outermost shell is **1** (Oxygen).

### Final Answer:
**1 element (Oxygen)** needs two more electrons to achieve an octet.

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