Adsorption
Adsorption is when atoms or molecules stick to the outer surface of a solid instead of soaking in.
Dust sticks to a wooden shelf the way adsorption works. The dust settles on top of the wood — it does not soak in. Each tiny dust particle clings to the outer surface and stays there. The shelf holds the dust on its face, not inside it.
Explaining adsorption by grade level
Think of dust on a table. The dust sits on top of the table. It does not go inside the wood. Charcoal works the same way with bad stuff in water. The bad parts stick to the outside of the charcoal.
Projects that explore adsorption
Adsorption is when molecules stick to the outer surface of a solid. Activated carbon filters use this process to grab chlorine from water as it flows past the carbon granules. Once the surface fills up, new chlorine passes through without sticking, and the filter fails.
Malathion kills flies within 30 minutes on its own, but activated carbon may change that outcome. When molecules stick to the outer surface of a solid rather than soaking in, they become unavailable to cause harm. This experiment tests whether coating poisoned bananas with activated carbon solution can protect flies from malathion by trapping the pesticide on the carbon surface. You spray malathion on overripe bananas, add activated carbon solution at different concentrations to some of them, then count surviving flies over one hour. The results show whether higher doses of activated carbon protect more flies from the pesticide.