Chemical Properties and Changes Properties Properties of matter

Chemical Properties and Changes

Properties • Properties of matter help identify objects. • Properties are either physical or chemical.

Properties • A chemical property is the ability or inability of a substance to combine with or change into one or more new substances.

Physical Properties & Changes • Physical properties can be observed without changing the substance.

Physical Properties & Changes • A physical change is a change in which the physical properties of a substance change but the identity of the substance remains the same.

Physical Properties & Changes • Dissolving is a process in which substances mix evenly with one another.

Chemical Properties • Examples: burning or rusting. • Some substances do not react. • To observe chemical properties, you must change the substance.

Chemical Changes • Chemical changes change one substance into another substance.

Chemical Changes • Usually chemical changes cannot be easily reversed. • Also called a chemical reaction.

Chemical Change • Occurs when substances gain (absorb) or lose (release) energy • (i. e. ) baking a cake, burning a match, a nail rusting

Chemical Changes (verbs-ACTION)

Chemical Changes (verbs-ACTION) • All chemical changes produce substances that are different from the starting substances.

Chemical Changes (verbs-ACTION) – A compound is decomposed into its elements. or – Two elements join to form a compound.

Signs of Chemical Change • There are signs you can look for that tell you when a new substance is present, and a chemical reaction has taken place.

Signs of Chemical Change (GCHOP) 1. Gas Production – bubbles form in a solution 2. Color Change – fall leaves changing color 3. Heat (Temperature Change) Releases energy (gets hot) or absorbs energy (gets cold)

Signs of Chemical Change 4. Odor- reaction gives off a distinctive smell 5. Precipitate – a solid forms out of solutions The key is that a new substance with a new chemical identity (chemical formula) is made!

8. 1 Chemical Properties and Changes Which is a chemical change? A boiling B burning C dissolving D melting

8. 1 Chemical Properties and Changes Which is NOT a chemical change? A sodium metal and chlorine gas react to form salt B salt dissolving in water C paper burning D iron rusting

Which is NOT a physical change? A melting B boiling C dissolving D burning

Which is a chemical change? A copper turning green from exposure to air B drying clothes C ice melting D none of the above

Which is a chemical property? A boils at 100°C B has a volume of 500 ml C does not rust D has a luster

Which of the following is a physical change? A hydrogen burning B iron rusting C copper turning green when exposed to air D none of the above