Connectivity
Both nitrogens attach directly to the carbonyl carbon.
That creates amide-like electronic coupling.
Molecular compound · carbonyl diamide
Urea
CH₄N₂O
Urea is CH₄N₂O with structure H₂N–C(=O)–NH₂. Both nitrogen atoms are electronically coupled to the carbonyl group.
Biological distinction: urea is a defined compound; urine is a complex mixture that can contain urea.
Essentials
One carbonyl carbon is bonded to two amino groups.
The condensed structure immediately shows why urea is not simply an amine plus a carbonyl placed nearby.
Detail
Resonance changes the C–N bonds from pure single-bond behavior.
Nitrogen lone-pair donation into the carbonyl system gives partial C–N double-bond character and favors planarity.
Planarity
Conjugation restricts free C–N rotation.
This is an intramolecular electronic effect.
Understand
Urea combines resonance inside the molecule with hydrogen bonding between molecules.
N–H groups can donate hydrogen bonds and the carbonyl oxygen can accept them.
Two levels
Inside: resonance. Between molecules: hydrogen bonding.
Keeping those levels separate prevents conceptual confusion.
Reference identifiers
Names and identifiers that pin down the chemical identity.
| Formula | CH₄N₂O |
|---|---|
| CAS Registry Number | 57-13-6 |
| PubChem CID | 1176 |
Advanced
Push past the first model without losing the simple picture.
Are the C–N bonds ordinary single bonds?
Not completely; resonance gives partial double-bond character.
Is urea basic like ammonia?
Much less at nitrogen because lone-pair density is delocalized into the carbonyl.
Is urea the same as urine?
No. One is a compound; the other is a mixture.
Constituent elements