EXPLORING PROPERTIES OF MATERIALS

EXPLORING PROPERTIES OF MATERIALSPOLYMERS & COMPOSITESOrganic compound a compound containing atoms of carbon bonded to one another and to other kinds of atoms (ex. hydrogen, oxygen, nitrogen).

*Carbon is present in more than 2 million known compounds!Carbon can form this many different compounds because of 2 properties:(1) carbon atoms can form 4 covalent bonds (maximum)(2) carbon atoms can form chains, branched chains, and rings

Polymer a large, complex molecule built from smaller molecules bonded together.

Monomer the smaller molecules from which polymers are built.

Polymers form when chemical reactions link monomers in a repeating pattern.What are some natural polymers?Cellulose fibers that make up cell walls of plants.

Animal polymers: spider webs, silk, wool, fingernails, etc. (all protein compounds)

Synthetic PolymersThe starting materials for most polymers are coal and oil.

Plastics common synthetic polymers that can be molded or shaped.

Synthetic polymers include: carpet, clothing, adhesives, insulation, etc.

[Figure 5 page 71]CompositesComposites combine two or more substances as a new material with different properties.

By using two or more substances in a composite, chemists can make a new material that works better than either one alone.A Natural CompositeWood is a common natural composite. Wood is made from cellulose and lignin.

Synthetic CompositesExamples: Fiberglass Graphite composites carbon nanotube composites

METALS & ALLOYSAlloy a mixture made of two or more elements that has the properties of a metal.

What are the properties of metals?

The properties of an alloy can differ greatly from those of its individual elements.

Alloys are generally stronger and less likely to react with air or water than pure metals.

Bronze CymbalBrass Trumpet

Other common alloys include:carbon steelstainless steelplumbers soldersterling silverdental amalgampewter

[Figure 9 page 82]Ceramics & GlassCeramics hard, crystalline solids made by heating clay and other materials to high temperatures.

Properties of Ceramics:Ceramics are brittleCeramics resist moistureCeramics do not conduct electricityCeramics can withstand extremely high temperaturesUses of CeramicsFood storageRoofing tilesBricksSewer pipesInsulators in electric equipment & light fixturesOven wallsSpace shuttle insulationGlassGlass a clear, solid material with no crystal structure, created by heating sand to a very high temperature.

Uses of Glass:WindowsBottles & jarsLensesCooking surfaces & cookwareLaboratory glasswareOptical fibersOptical fiber a threadlike piece of glass or plastic that can be used for transmitting light.

The light that moves through an optical fiber is reflected within the fiber.

A pair of optical fibers the thickness of a human hair can carry 625,000 phone calls at one time.One quarter pound of glass fiber can replace over two tons of copper telephone and cable television lines.