Physical & Chemical Properties Scientists use characteristic properties to identify matter

Physical Properties Many physical properties can be observed or measured Many physical properties can be observed or measured Mass, volume, density (mass/volume) Mass, volume, density (mass/volume) Color, shape, odor, texture Color, shape, odor, texture Melting, boiling point Melting, boiling point Strength, hardness, Strength, hardness, Magnetism Magnetism Ability to conduct electricity or heat Ability to conduct electricity or heat State of matter (solid, liquid, gas) State of matter (solid, liquid, gas)

Specific Temperatures of Phase Changes SubstanceMelting Pt o CBoiling Pt o C Water Gold Carbon Mercury Nitrogen Oxygen NaCl

Density All matter has mass, volume & density All matter has mass, volume & density Density determines whether an object will float or sink Density determines whether an object will float or sink Density is the amount of mass in a volume Density is the amount of mass in a volume Density = mass/volume Density = mass/volume D=m/V D=m/V

Density Examples Chemical Substance Formula Density in g/cm 3 Air mixture HeliumHe WaterH IceH Steelmixture7.8 IronFe7.86

Physical properties help to determine uses Copper used in electrical power lines Copper used in electrical power lines Antifreeze (ethylene glycol) remains a liquid at temperature that would freeze or oil water in a car radiator Antifreeze (ethylene glycol) remains a liquid at temperature that would freeze or oil water in a car radiator Aluminum foil is lightweight, yet durable, water resistant and flexible Aluminum foil is lightweight, yet durable, water resistant and flexible

Chemical Properties Describes how a substance reacts Describes how a substance reacts Reactivity – the ability of a substance to combine chemically with another substance (oxygen, acid, water or other substances) Reactivity – the ability of a substance to combine chemically with another substance (oxygen, acid, water or other substances) Iron reacts with oxygen to make rust Fe 2 O 3 Iron reacts with oxygen to make rust Fe 2 O 3 Flammability – the ability of a substance to react in the presence of oxygen and burn when exposed to a flame Flammability – the ability of a substance to react in the presence of oxygen and burn when exposed to a flame Wood is flammable Gold is nonflammable Wood is flammable Gold is nonflammable

Comparisons SubstancePhysical Chemical Helium less dense airnonflammable Woodgrainy textureflammable Baking Sodawhite powderreacts w/vinegar Rubbing alcoholclear liquidflammable Ironmalleablereacts with oxygen

Physical Change A change of matter from one form to another without a change in chemical properties A change of matter from one form to another without a change in chemical properties Torn paper Torn paper Melting ice Melting ice Crushing a can Crushing a can Sanding wood Sanding wood Dissolving sugar Dissolving sugar

Although a physical change takes place, a substance will maintain its chemical properties Although a physical change takes place, a substance will maintain its chemical properties Melting, freezing and evaporation - all changes of state - are physical changes because the identity of the substance does not change Melting, freezing and evaporation - all changes of state - are physical changes because the identity of the substance does not change ice, water, steam – all are water! ice, water, steam – all are water! Physical changes are often easily reversed. Physical changes are often easily reversed.

Mixtures can be separated using physical and chemical properties. Mixtures can be separated using physical and chemical properties. Physical properties such as solubility, magnetism, density and size can help separate mixtures. Physical properties such as solubility, magnetism, density and size can help separate mixtures.

Chemical change A change that occurs when a substance changes composition by forming one or more new substances. A change that occurs when a substance changes composition by forming one or more new substances. Chemical changes are always accompanied by physical changes. Chemical changes are always accompanied by physical changes.

Evidence of Chemical Reaction Chemical change or “reactivity” results in Temperature change (always) Temperature change (always) Flame or light or explosion Flame or light or explosion Change color Change color Bubbling (gasses) [NOT BOILING] Bubbling (gasses) [NOT BOILING] Oxidation (rusting or tarnishing) Oxidation (rusting or tarnishing) Solid formation (precipitation) [NOT FREEZING] Solid formation (precipitation) [NOT FREEZING]