CHEMICAL PROPERTIES Chapter 3 - 3

IDENTIFYING CHEMICAL PROPERTIES Chemical properties are the ability of substances to change into entirely new substances. The new substances have a different set of properties from the original substances.

REACTIVITY & NONREACTIVITY Reactivity is the ability of a substance to change into one or more substances. Flammability, a type of reactivity, is the ability to burn. Wood burns = Flammable Smoke & ash don’t = nonflammable Rusting is reactivity of iron to oxygen.

COMPARING PROPERTIES If the property is physical, you can observe that property without changing the identity. Chemical properties are not easy to see until the change is taking place, like when wood is burning.

CHARACTERISTIC PROPERTIES Characteristics that are the most useful in identifying substances are called characteristic properties. Density and reactivity are two of these properties. Scientists rely on these to identify and classify substances.

CHEMICAL CHANGES & NEW SUBSTANCES A chemical change happens when a substance changes into something new. You can usually see a chemical change.

SIGNS OF CHEMICAL CHANGES: Chemical changes often cause color changes, fizzing or foaming, a temperature change, production of sound, light, or odor. Chemical changes cannot be “undone” because the substance’s identity changes.

EXAMPLES OF CHEMICAL CHANGES: Soured milk smells bad because bacteria have formed new substances in the milk. Statue of Liberty turned green because the copper reacts to the moist air. Effervescent tablets bubble because the ingredients react with water. Hot gases from a rocket form because hydrogen and oxygen join to make water.

THE END CHAPTER 3 - 3