* Elements are the simplest forms of matter and cannot be broken down further by chemical means. Heating an element might cause it to change state (solid to liquid or gas), but it wouldn't fundamentally change its composition.

* Compounds are formed by the chemical combination of two or more elements. When heated, compounds can break down into their constituent elements, often producing visible changes in color and state.

The production of vapor and black material suggests a chemical decomposition. The white substance likely contained elements that were bonded together, and the heat caused the bonds to break, releasing some elements as vapor and leaving behind other elements as the black material.

Example: Think of heating baking soda (sodium bicarbonate, a compound). It decomposes to produce sodium carbonate (white powder), carbon dioxide (gas), and water vapor (invisible gas).