All element in 3rd period have

Options

A. An atomic number 3
B. 3 complete sub-shells
C. Valence electrons shell
D. 3 electrons less than the octet

Answer

To answer the question regarding the elements in the 3rd period, we will analyze the periodic table and the electronic configuration of the elements in this period.

### Step-by-Step Solution:

1. **Identify the Elements in the 3rd Period**:
The elements in the 3rd period of the periodic table are:
- Sodium (Na)
- Magnesium (Mg)
- Aluminium (Al)
- Silicon (Si)
- Phosphorus (P)
- Sulfur (S)
- Chlorine (Cl)
- Argon (Ar)

2. **Determine the Electronic Configuration**:
- Sodium (Na): 1s² 2s² 2p⁶ 3s¹
- Magnesium (Mg): 1s² 2s² 2p⁶ 3s²
- Aluminium (Al): 1s² 2s² 2p⁶ 3s² 3p¹
- Silicon (Si): 1s² 2s² 2p⁶ 3s² 3p²
- Phosphorus (P): 1s² 2s² 2p⁶ 3s² 3p³
- Sulfur (S): 1s² 2s² 2p⁶ 3s² 3p⁴
- Chlorine (Cl): 1s² 2s² 2p⁶ 3s² 3p⁵
- Argon (Ar): 1s² 2s² 2p⁶ 3s² 3p⁶

3. **Analyze the Common Features**:
All elements in the 3rd period have their outermost electrons filling the 3s and 3p orbitals. The maximum number of electrons that can occupy these orbitals is 8 (2 in the 3s and 6 in the 3p).

4. **Conclusion**:
Therefore, all elements in the 3rd period have a total of 8 electrons in their outermost shell (valence shell), which corresponds to the electronic configuration ending in 3s² 3p⁶ for Argon, the noble gas.

### Final Answer:
All elements in the 3rd period have a total of 8 electrons in their outermost shell.

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