Overview
This lecture explains electron configurations, focusing on how electrons fill orbitals and the rules atoms follow to achieve stability.
Electron Configuration & Orbitals
- Electron configuration shows how electrons are distributed among an atom's orbitals.
- The first orbital holds a maximum of two electrons.
- The second and third orbitals can each hold up to eight electrons.
- The lecture focuses on atoms up to the third orbital in the periodic table.
Stability and the Duet/Octet Rules
- Atoms are stable when their outermost orbital is full.
- Hydrogen has one electron and is unstable because its orbital isn’t full.
- Helium has two electrons, filling its first orbital and making it stable.
- Stable atoms are described as "happy" and do not typically react.
- Hydrogen and Helium obey the duet rule (two electrons for stability).
- All other atoms strive for eight electrons in their outermost orbital, following the octet rule.
Examples of Electron Configurations
- Nitrogen has five electrons in its outermost orbital and is unstable.
- Oxygen has six electrons in its outermost orbital and is unstable.
- Neon has eight electrons in its outermost orbital, satisfies the octet rule, and is stable.
Key Terms & Definitions
- Electron Configuration — the arrangement of electrons in an atom's orbitals.
- Orbital — the region around a nucleus where electrons are found.
- Stable Atom — an atom with a full outer orbital that does not react easily.
- Duet Rule — rule stating hydrogen and helium are stable with two electrons in their outermost orbital.
- Octet Rule — rule stating most atoms are stable with eight electrons in their outermost orbital.
Action Items / Next Steps
- Review examples of electron configurations for the first ten elements.
- Practice identifying if an atom is stable using the duet and octet rules.