Colloids stabilize suspensions because their tiny particles don’t easily settle down. This stability comes mainly from two mechanisms:
1. Electrostatic (Charge) Stabilization
- Most colloidal particles carry an electric charge on their surface.
- Because like charges repel each other, the particles stay apart and don’t clump together.
- Example: Clay particles in water carry negative charges, which prevents them from settling quickly.
2. Steric Stabilization
- Sometimes, colloids are coated with polymers or surfactants.
- These layers act like a “shield” that prevents particles from sticking together.
- Even if charges are neutralized, the bulky coating keeps particles separated.
Why this matters in suspensions
- In a normal suspension, particles are larger and settle down due to gravity.
- In a colloid, particles are very small (1–1000 nm) and constantly move due to Brownian motion (random motion in the liquid).
- This motion plus charge/steric effects keeps them uniformly dispersed.
In short: Colloids stabilize suspensions by repulsion (charge) and protection (polymer/surfactant coating), which stop the particles from clumping or settling.