Materials and their uses by Asad Ali

MATERIALS AND THEIR USES.A presentation on Properties and types of Materials.

WHAT ARE MATERIALS?A material is a physical substance used to make things.Metals, Plastics, Glass, Ceramics and Fibres are some of the main categories of materials.If we look around, everything we see are made from a material, sometime more than one.

TYPES OF MATERIALS.MetalsA metal is a material (an element, compound, or alloy) that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable — that is, they can be hammered or pressed permanently out of shape without breaking or cracking — as well as fusible (able to be fused or melted) and ductile (able to be drawn out into a thin wire). About 91 of the 118 elements in the periodic tableare metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms.Astrophysicists use the term "metal" to collectively describe all elements other than hydrogen and helium.

Non-metalsIn chemistry, a nonmetal (or non-metal) is a chemical element that mostly lacks metallic attributes. Physically, nonmetals tend to be highly volatile (easily vaporised), have low elasticity, and are good insulators of heat and electricity; chemically, they tend to have high ionization energy and electronegativityvalues, and gain or share electrons when they react with other elements or compounds. Seventeen elements are generally classified as nonmetals; most are gases (hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon and radon); one is a liquid (bromine); and a few are solids (carbon, phosphorus, sulfur, selenium, and iodine).

PROPERTIES OF A MATERIAL.Properties of Metal.Metals in general have high electrical conductivity, high thermal conductivity, and high density. Typically they are malleable and ductile, deforming under stress without cleaving. In terms of optical properties, metals are shiny and lustrous.

Properties of Non-Metal.Nonmetals have high ionization energies and electronegativities. They are generally poor conductors of heat and electricity. Solid nonmetals are generally brittle, with little or no metallic luster. Most nonmetals have the ability to gain electrons easily. Nonmetals display a wide range of chemical properties and reactivities.