You need 8 $ e^- $ to fill your shell

Lewis structures

Exceptions to the Octet Rule

• Some only need 6
  • Al and B
• Some only need 2
  • H and He
• Some can have 12
  • 3rd period
  • $ SF_6 $ , S has 12
  • $ PCl_5 $ , P has 10
  • Pretty common actually
• Odd number of electrons
  • These shouldn’t even exist really but other rules make it so they do ig
  • NO

Chatgpted drawn out explanation:

The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable configuration with eight electrons in their valence shell. While a useful guideline, there are notable exceptions to this rule.

1. Incomplete Octet

• Elements: Group 2 and 3 elements (Be, B, Al) often have fewer than eight electrons in their valence shell.
• Explanation: These elements have a low Electronegativity and readily form bonds by sharing electrons. However, they may not achieve a full octet due to their limited number of valence electrons.
• Example: Boron trifluoride ( $ BF_3 $ ). Boron has only three valence electrons, forming three bonds with fluorine atoms. This leaves boron with only six electrons in its valence shell.

2. Expanded Octet

• Elements: Elements in Period 3 and beyond (from P to the right) can accommodate more than eight electrons in their valence shell.
• Explanation: These elements have available d orbitals in their valence shell, which can participate in bonding. This allows them to form more than four Covalent Bonds and expand their octet.
• Example: Sulfur hexafluoride ( $ SF_6 $ ). Sulfur has six valence electrons and forms six bonds with fluorine atoms. This results in 12 electrons around sulfur, exceeding the octet rule.

3. Odd Number of Electrons

• Elements: Elements with an odd number of valence electrons, such as nitrogen dioxide ( $ NO_2 $ ).
• Explanation: These molecules cannot achieve an even number of electrons around each atom, making it impossible for all atoms to have a complete octet.
• Example: Nitrogen dioxide ( $ NO_2 $ ). Nitrogen has five valence electrons, and oxygen has six. The molecule has a total of 17 valence electrons, resulting in an odd number of electrons around each atom.

4. Transition Metal Ions

• Elements: Transition metals often form ions with incomplete d-orbitals.
• Explanation: The d-orbitals are involved in bonding and can hold up to ten electrons. However, transition metal ions often have fewer than eight electrons in their valence shell, particularly in complex ions.
• Example: Copper(II) ion ( $ Cu^{2+} $ ). Copper has a d-orbital configuration of $ 3d^{10} $ in its neutral state. When it loses two electrons to form $ Cu^{2+} $ , it has a $ 3d^9 $ configuration. This configuration has only nine electrons in its valence shell.

Summary

The octet rule is a useful simplification but doesn’t always hold true. Understanding the exceptions to the octet rule is crucial for accurately predicting and explaining the behavior of molecules and ions.