The Properties of MatterThe Properties of Matter

Looking at Matter at the Looking at Matter at the Molecular LevelMolecular Level

Describing MatterDescribing Matter

• The characteristics or properties of The characteristics or properties of an object can help you identify the an object can help you identify the substance.substance.

• Substances have unique properties Substances have unique properties and characteristics.and characteristics.

Properties of MatterProperties of Matter

• There are: There are: • Physical PropertiesPhysical Properties• Chemical PropertiesChemical Properties

Physical PropertiesPhysical Properties

Things that describe the object are Things that describe the object are physical properties.physical properties.

Physical properties can also be observed Physical properties can also be observed or measured without changing the identity or measured without changing the identity of the matter.of the matter.

Physical propertiesPhysical properties

Boiling pointBoiling point - Viscosity- ViscosityMelting pointMelting point - Density- DensityVolatilityVolatility - Malleability- MalleabilityColorColor - Electrical conductivity- Electrical conductivityTasteTasteHardnessHardnessOdorOdorDuctilityDuctility

Chemical PropertiesChemical Properties

Chemical properties describe a substance based Chemical properties describe a substance based on its ability to change into a new substance with on its ability to change into a new substance with different properties.different properties.

Chemical properties cannot be observed with Chemical properties cannot be observed with your senses.your senses.

Chemical properties aren’t as easy to observe as Chemical properties aren’t as easy to observe as physical properties.physical properties.

Chemical propertiesChemical properties

Burns in airBurns in airExplodesExplodesTarnishesTarnishesDecomposes when heatedDecomposes when heatedReacts with water, metals, etc.Reacts with water, metals, etc. Is toxicIs toxicDecomposes by electricityDecomposes by electricity

Matter undergoes changesMatter undergoes changes

There are 2 types of changes:There are 2 types of changes:

Physical changesPhysical changesChemical changesChemical changes

Physical ChangesPhysical Changes

A physical change is a change that affects one or A physical change is a change that affects one or more physical properties of a substance.more physical properties of a substance.

Physical changes do not form new substances! Physical changes do not form new substances! EX: ice melting or sugar dissolvingEX: ice melting or sugar dissolving

Physical changes are easy to undo.Physical changes are easy to undo.

Physical ChangesPhysical Changes

Crumpling a piece of paperCrumpling a piece of paperPulling copper into a thin wirePulling copper into a thin wireCutting woodCutting woodTearing a piece of aluminum foilTearing a piece of aluminum foilBreaking glassBreaking glassCloud forming in the skyCloud forming in the skyFreezing waterFreezing water

Chemical ChangesChemical Changes

A chemical change occurs when one or more A chemical change occurs when one or more substances are changed into entirely new substances are changed into entirely new substances with different properties.substances with different properties.

You can observe chemical properties only when a You can observe chemical properties only when a chemical change might occur!chemical change might occur!

Examples of chem. changes:Examples of chem. changes:

baking a cakebaking a cake

rustingrusting

Chemical changesChemical changes

Burning a log of woodBurning a log of woodCombustion of gasolineCombustion of gasolineDigestion of foodDigestion of foodLightning a matchLightning a matchRusting nailRusting nailCooking a cakeCooking a cakePhotosynthesisPhotosynthesis

Signs of chemical changesSigns of chemical changes

Color changeColor changeFizzing or bubbling (gas production)Fizzing or bubbling (gas production)Energy changeEnergy changeProduction of light, sound, or odor.Production of light, sound, or odor.Formation of a precipitateFormation of a precipitate

Chemical changes are not usually Chemical changes are not usually reversible!reversible!