Physical Properties Physical Properties of Matterof Matter

Physical Property – any characteristic of a Physical Property – any characteristic of a material that can be observed or measured material that can be observed or measured without changing the composition (makeup) of without changing the composition (makeup) of the substances in the material.the substances in the material. These properties are used to identify a material or These properties are used to identify a material or

chose which material to use for a certain task.chose which material to use for a certain task. One must look at more than one physical property One must look at more than one physical property

to make their decision. to make their decision.

Examples of physical Examples of physical propertiesproperties

ViscosityViscosity ConductivityConductivity MalleabilityMalleability HardnessHardness Melting and Boiling PointMelting and Boiling Point DensityDensity

ViscosityViscosity

Viscosity – the tendency of a liquid to Viscosity – the tendency of a liquid to keep from flowing (its resistance to keep from flowing (its resistance to flowing)flowing) Thick liquids have a high viscosity.Thick liquids have a high viscosity. Thin, runny liquids have a low viscosity.Thin, runny liquids have a low viscosity. Viscosity is usually decreased when the Viscosity is usually decreased when the

liquid is heated.liquid is heated.

ConductivityConductivity

Conductivity Conductivity – material’s ability to allow – material’s ability to allow heat to flowheat to flow Metals conduct heat well…called Metals conduct heat well…called

conductors.conductors. If conducts heat well, usually conducts If conducts heat well, usually conducts

electricity well.electricity well.

Ouch!

MalleabilityMalleability MalleabilityMalleability – the ability of a solid to be – the ability of a solid to be

hammered without shattering.hammered without shattering. Most metals are malleable.Most metals are malleable. If not malleable, then we call substances If not malleable, then we call substances brittle brittle

because it breaks when hammered because it breaks when hammered ((like ice).like ice).

HardnessHardness

Compare hardness by Compare hardness by scratching. scratching.

If a material can scratch If a material can scratch another, then it is harder than another, then it is harder than the other material.the other material. Stainless steel can scratch Stainless steel can scratch

copper. Thus, steel is harder copper. Thus, steel is harder than copper.than copper.

A diamond is hardest known A diamond is hardest known material.material.

Melting and Boiling Melting and Boiling PointsPoints

Melting PointMelting Point – – temperature at which a temperature at which a substance changes from substance changes from solid to liquid solid to liquid

Boiling Point –Boiling Point – temperature at which a temperature at which a substance changes from substance changes from a liquid to a gas a liquid to a gas

DensityDensityDensity – ratio of a substance’s mass to its Density – ratio of a substance’s mass to its

volumevolume

Density = mass/VolumeDensity = mass/Volume

Mass – gMass – g Volume - mL or cmVolume - mL or cm33 or cc or cc Density – g/mL or g/cmDensity – g/mL or g/cm33

DensitiesDensitiesMaterialMaterial Density (gm/ cmDensity (gm/ cm3)3)

Water at 4 C Water at 4 C 1.00001.0000

Water at 20 C Water at 20 C 0.9980.998

Gasoline Gasoline 0.700.70

Magnesium Magnesium 1.71.7

Copper Copper 8.3-9.08.3-9.0

Gold Gold 19.319.3

Ice at 0 C Ice at 0 C 0.920.92

Air Air 0.0012930.001293

Helium Helium 0.0001780.000178

Separating Materials via Separating Materials via Physical PropertiesPhysical Properties

FiltrationFiltration – separating materials – separating materials based on the size of their particles based on the size of their particles (like straining spaghetti or tea)(like straining spaghetti or tea)

Distillation Distillation – process that – process that separates the substances in a separates the substances in a solution based upon boiling points. solution based upon boiling points. Distillation is done by heating a liquid Distillation is done by heating a liquid

until it boils, capturing and cooling the until it boils, capturing and cooling the hot vapors, then collecting the hot vapors, then collecting the condensed vapors. As a result the condensed vapors. As a result the impurities (or unwanteds) are left impurities (or unwanteds) are left behind in the 1behind in the 1stst container. container.

Physical ChangePhysical Change Physical changePhysical change – occurs when some of the – occurs when some of the

properties of a material change, but the substances in properties of a material change, but the substances in the material remain the same.the material remain the same.Examples: Examples: Cutting hair (hair is still hair even though it looks different)Cutting hair (hair is still hair even though it looks different) Slicing a tomatoSlicing a tomato Ironing a shirtIroning a shirt Freezing water into iceFreezing water into ice

Some physical changes are reversible, which means Some physical changes are reversible, which means that you can take the substance back to the original.that you can take the substance back to the original. Ice melts and can become ice againIce melts and can become ice again When you cut hair off, you can’t put it back.When you cut hair off, you can’t put it back.