Calculator Inputs
Build a simple diatomic species, choose an ordering rule, and generate an MO occupancy view instantly.
Example Data Table
| Species | Valence electrons | Ordering | Bond order | Magnetism | HOMO |
|---|---|---|---|---|---|
| N2 | 10 | s-p mixing | 3.00 | Diamagnetic | σ2p |
| O2 | 12 | Standard second-row | 2.00 | Paramagnetic | π*2p |
| B2 | 6 | s-p mixing | 1.00 | Paramagnetic | π2p |
| CN− | 10 | s-p mixing | 3.00 | Diamagnetic | σ2p |
Formula Used
Valence electron count: total electrons = valence electrons from Atom A + valence electrons from Atom B − positive charge + negative charge magnitude.
Bond order: bond order = (bonding electrons − antibonding electrons) ÷ 2.
Magnetism rule: any unpaired electron makes the species paramagnetic. Zero unpaired electrons makes it diamagnetic.
Ordering rule: the viewer uses either an s-p mixing sequence or a standard second-row sequence. Auto mode applies a common classroom approximation, while manual mode lets you compare both patterns.
How to Use This Calculator
- Select Atom A and Atom B for the diatomic species.
- Enter the net charge. Use positive for cations and negative for anions.
- Keep Auto select for a quick estimate, or switch the ordering model for comparison.
- Add a manual electron override only when you want to test a custom scenario.
- Press Submit to place electrons into the molecular orbitals.
- Review bond order, magnetic behavior, HOMO, LUMO, SOMO, and the orbital occupancy viewer. Use the export buttons to save the result as CSV or PDF.
FAQs
1. What does this viewer calculate?
It distributes valence electrons into molecular orbitals, then reports bond order, magnetic behavior, HOMO, LUMO, SOMO, and a readable occupancy diagram.
2. Which molecules work best here?
It works best for simple diatomic molecules and ions, especially first-shell and second-row classroom examples such as N2, O2, B2, CO, and CN−.
3. Why can I change the ordering model?
Some second-row species are taught with s-p mixing, while others use the standard sequence. Switching models helps you compare classroom conventions and see how frontier orbitals shift.
4. What does a positive bond order mean?
A positive bond order suggests a bonding interaction remains after antibonding occupancy is subtracted. Larger values usually indicate stronger bonding and shorter internuclear distance.
5. Why is oxygen shown as paramagnetic?
In the common MO model for O2, electrons occupy separate π* orbitals before pairing. Those unpaired electrons make oxygen paramagnetic.
6. What is HOMO and LUMO?
HOMO is the highest occupied molecular orbital. LUMO is the lowest orbital that still has unoccupied space and can accept electron density.
7. When should I use the manual electron override?
Use it for teaching examples, quick checks, or custom comparison cases when you want to test an electron count without changing the chosen atoms.
8. Is this a full quantum chemistry simulator?
No. It is a fast educational viewer built around standard MO theory rules, not a numerical electronic structure solver with basis sets or geometry optimization.