Study Notes on Valence Electrons and Ion Formation

Valence Electrons

• Valence electrons are the outermost electrons in an atom.
• Highest energy level determines the valence electrons.

Noble Gas Configuration

• Selenium: Noble gas configuration is the core followed by $4s^2 3d^{10} 4p^4$.
• Total valence electrons in Selenium: 6 (2 from $4s$ and 4 from $4p$).

Electron Distribution

• Visualize with Lewis dot diagrams: Represent valence electrons as dots around the element's symbol, without pairing until necessary.
• Atoms aim for a full valence shell (octet) to achieve stability.

Isoelectronic Concept

• Isoelectronic refers to having the same electron configuration as a noble gas.
• For elements with higher atomic numbers, the first energy level wants 2 electrons, others want 8.

Charge Minimization

• Atoms generally prefer to minimize charge when gaining or losing electrons.
• Nonmetals gain electrons, forming negative ions (anions), while metals lose electrons to form positive ions (cations).

Anion Naming

• Negative ions end with the suffix -ide (e.g., Selenium becomes Selenide).
• Replace the last syllable of the element name with -ide when naming anions.

Cation Naming

• Positive ions are simply named as the element (e.g., Calcium ion).
• No specific suffix is needed for naming cations.

Summary of Electron Behavior

• Metals lose electrons to achieve a noble gas configuration (forming cations).
• Nonmetals gain electrons (forming anions).
• Stable configurations aim for minimal charge, resulting in a preference for lower ionic charges (closer to zero).