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capt_yellowbeard t1_j1mppah wrote

Sure. The things you listed are all state changes - changes between the states of matter - solid, liquid, gas, and (not mentioned in your post) plasma.

Evaporation is liquid to gas. Sublimations is straight from solid to gas (think “what dry ice does”). State changes are driven by a combination of the amount of energy in a substance and pressure. However, when things change states their molecular structures don’t change. Water vapor, liquid water, and solid water (ice) are all the same chemical substance (H2O) just in different states.

For a chemical change, molecules must change. This means that atoms must break and/or create bonds with one another. This happens generally by sharing or exchanging electrons in the outermost shell (called the valence shell) of the atoms. So there will be DIFFERENT molecules after a chemical change then there were at the beginning. Examples of this include burning paper (in which cellulose breaks down to glucose and glucose breaks down to CO2 and H2O) or photosynthesis (which is sort of the reverse chemical reaction) in which plants use CO2 and H2O to make glucose (C6H12O6).

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