There are actually more than 7 indicators of a chemical change, but here are some of the most common and reliable ones:

1. Change in Color: A change in color often indicates that a new substance has been formed. For example, when iron rusts, it changes from a silvery gray color to a reddish-brown color.

2. Formation of a Precipitate: A precipitate is a solid that forms from a solution during a chemical reaction. This is a sign that a new substance has been created. For example, when you mix solutions of lead nitrate and potassium iodide, a yellow precipitate of lead iodide forms.

3. Production of a Gas: The release of a gas, often accompanied by bubbling or fizzing, indicates a chemical change. For example, when baking soda reacts with vinegar, carbon dioxide gas is produced.

4. Change in Temperature: Chemical reactions can release or absorb heat, causing a change in temperature. An increase in temperature indicates an exothermic reaction, while a decrease indicates an endothermic reaction. For example, burning wood releases heat, making it an exothermic reaction.

5. Change in Odor: A change in odor suggests that a new substance has been formed. For example, when you burn a piece of paper, it releases a distinct odor.

6. Production of Light: Some chemical reactions produce light. This is known as chemiluminescence. For example, fireflies produce light through a chemical reaction.

7. Formation of a New Substance with Different Properties: This is the most fundamental indicator of a chemical change. The new substance will have different physical and chemical properties than the original substances. For example, when you mix baking soda and vinegar, the resulting solution has different properties than either of the original ingredients.

Remember that some of these indicators can also be observed during physical changes. For example, melting ice is a physical change, but it involves a change in temperature. It's important to consider all the evidence before determining whether a change is chemical or physical.