7.Usage of metals
Some metals and metal alloys possess high structural strength per unit mass, making them useful materials for carrying large loads or resisting impact damage. Metal alloys can be engineered to have high resistance to shear, torque and deformation. However the same metal can also be vulnerable to fatigue damage through repeated use, or from sudden stress failure when a load capacity is exceeded. The strength and resilience of metals has led to their frequent use in high-rise building and bridge construction, as well as most vehicles, many appliances, tools, pipes, non-illuminated signs and railroad tracks.
The metals are one of the three groups of elements as distinguished by their ionisation and bonding properties, along with the metalloids and nonmetals. The framing in all of these buildings is usually wood, held together with steel or iron nails. The inside walls are often composed of wallboard, which is made from the mineral gypsum. Electricity, often made by burning petroleum, coal, or natural gas, is available by plugging into the wall outlet. Electricity flows along copper or sometimes aluminum wiring that's inside the walls.
Metals differ in their reactivity with other chemicals and this influences their uses.Activity Series of Metals"Recall qualitative descriptions of reactants and products in corrosion, acids on metals andcarbonates and neutralization"."Describe observable changes when metals react with dilute acids, water and oxygen". apply an appropriate atomic model (Rutherford model) to describe atomic structuredetermine the number of protons and neutrons in the nucleus of a neutral or charged atomdetermine the number of electrons orbiting the nucleus of a neutral or charged atom use the periodic table to describe some simple relationships between elements (maybe restri.cted to a very basic.
Historically, materials and their properties have been inextricably tied to the ability to withstand severe environments and to provide hardware that will operate successfully in multiple missions. An intimate knowledge of the materials, their composition, their reaction under various operating conditions, and their success and failure history will provide the designer with the ability to select the right material for any given task