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. Two elements join to form a compound. or

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) Gas Production – bubbles form in a solution Color Change – fall leaves changing color Heat (Temperature Change) Releases energy (gets hot) or absorbs energy (gets cold)

Signs of Chemical Change 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!

Which is a chemical change? A boiling B burning C dissolving D melting 8.1 Chemical Properties and Changes Which is a chemical change? A boiling B burning C dissolving D melting

Which is NOT a chemical change? 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