Have you ever wondered why your milk goes sour? Well, that's a chemical change!
Who the heck are you? And what the heck is a chemical change?
A chemical change. It occurs when two or more substances combine to form a new substance. For the most part, they tend to be irreversible except by further chemical reactions.
That's certainly helpful. But how do I identify these changes?
That's a good question and to answer it, we need to talk about chemical properties. Chemical properties are any of a material's properties that are present during or after a chemical reaction. This includes, but not limited to: flammability, reactivity, etc. You can identify changes by their chemical properties.
Eh, sure. Why not?
Could I have some examples?
Good question. The chemical bonds were broken and the atoms were rearranged to form a new substance; the baked brownies.
Right. So let's say you make brownies one day, you plop the batter into the oven and take it out later to have brownies! That's a chemical change!
That makes sense, but why did the batter turn into brownies?
Precisely! I think you got it!
Another example. You see that rusted car over there? Why do you think that car rusted?
The iron in the car came in contact with another substance, oxygen, causing an atomic reaction that resulted in the car getting rusted?
Aw come on, did he seriously just disappear? Oh well.. But at least now I know what chemical properties, changes, and reactions are..