the.com/colloid
Particles too big to dissolve, too small to settle — forever stuck in between.
means A mixture where tiny particles of one substance are dispersed evenly throughout another without fully dissolving — like milk, fog, or gelatin.
from Coined in the mid-1800s by Scottish chemist Thomas Graham, who built it from Greek 'kolla' meaning glue, plus '-oid' meaning 'resembling.' Graham was sorting substances by how they diffused through membranes, and noticed some — like starch and gelatin, literal glues — moved sluggishly and wouldn't crystallize, unlike quick, crystal-forming 'crystalloids.' So the word's root honestly means 'glue-like,' a nod to the gluey, non-crystalline behavior that first set these substances apart.
- size range
- 1 to 1000 nanometers, the awkward middle child
- tyndall effect
- scatters light, which is why fog glows in headlights
- everyday examples
- milk, blood, fog, and mayonnaise are all colloids
- stability trick
- stays suspended via electric charge, not luck