π What are Electron Domains?
Electron domains represent all regions around a central atom where electrons are likely to be found. Think of it as counting every 'zone' of electron density. Whether it's a single bond, a double bond, a triple bond, or a lone pair β each counts as one electron domain.
- βοΈ Single bond: Counts as one electron domain.
- βοΈ Double bond: Still counts as one electron domain (all those electrons are in the same 'zone').
- Records triple bond: You guessed it β one electron domain!
- π» Lone pair: Also counts as one electron domain.
βοΈ What are Bonding Domains?
Bonding domains are simpler. They only count the regions where atoms are bonded to the central atom. So, lone pairs don't count here!
- π€ Single bond: One bonding domain.
- π Double bond: One bonding domain.
- β±οΈ Triple bond: One bonding domain.
- π¨ Lone pair: Zero bonding domains (because no atoms are directly connected via that electron density).
π Electron Domains vs. Bonding Domains: Side-by-Side
| Feature |
Electron Domains |
Bonding Domains |
| Definition |
All regions of electron density around a central atom. |
Regions where atoms are bonded to the central atom. |
| Includes |
Single bonds, double bonds, triple bonds, and lone pairs. |
Single bonds, double bonds, and triple bonds. |
| Lone Pairs Count? |
Yes |
No |
| Example: $CO_2$ |
2 (two double bonds) |
2 (two double bonds) |
| Example: $H_2O$ |
4 (two single bonds + two lone pairs) |
2 (two single bonds) |
π Key Takeaways
- π‘ Electron domains consider all areas of electron density, while bonding domains only focus on bonded atoms.
- π§ͺ Lone pairs are the key difference! They contribute to electron domains but not bonding domains.
- π’ Understanding these concepts is crucial for predicting molecular geometry and polarity using VSEPR theory.