Sunday, 23 November 2008

F.3 I.S. Chemistry - Introduction to Metals and atomic structure

Chemistry – Metals and basic atomic structure 1) Metals are a categories of common used materials. 2) There’re 9 common properties of metals: Shiny, good conductors of electricity and heat, malleability(pressed into sheets), ductility(pulled into wires), strong(hard), high melting point and boiling point and high density. 3) There are exceptions for those properties, e.g. graphite(a form of carbon) is hard, shiny, good conductors electricity and high melting point; sodium is soft, low-melting and light. 4) Choosing the suitable metals usually refers to the strength, electrical conductivity, resistance to corrode in are, appearance and cost. For example, Gold is used for making jewellery because it’s high cost, shiny surface and resists corrosion. Treated aluminium is used for making window frames because aluminium oxide resists corrosion. 5) The history of usage on metals- Copper age (5k-3.5kBC), Bronze (mixture of copper and tin) age (3.5-1.5kBC) and Iron age (using iron and steel and sometimes other materials; shape-memory alloys and use of superconductivity; 1.5kBC afterwards) 6) Elements are thing that can’t be split up into anything simpler, e.g. carbon. They can be further classified into metals and non-metals (and metalloid). 7) Compound contains two or more compound through chemical reaction, e.g., burns carbon forms carbon dioxide. They may have independent properties from the original elements, e.g., H and O are flammable but H2O is water. 8) Mixture contains two or more elements or compounds, they are only mixed. 9) There’re 109 elements up to now which 92 is found in nature and the others were made by scientists. There’re 11 gases, 2 liquid(bromine and mercury) and the others are solids in room temperature and pressure. The 11 gases are H, N, O, F, Cl and 6 noble gases. 10) Comparing the metals and non-metals, the metals are usually silvery white (except gold and copper) and non-metals are usually dull and variously coloured. Sonorous-a sound produced when you hit it) for metals and other metals properties. 11) Metalloids have some properties from metals and non-metals and they are commonly used in industry. For example, silicon is a semi-conductor in transistors and silicon chips. 12) Atom is the basic constituent particle of an elements and the smallest, basic particle of an elements with diameters about 10-8cm and masses of 10-23g. An elements of substances is only made up of one kind of atoms. 13) The chemical symbols for elements are also the atomic symbols for their atoms. For example, C represents element carbon or carbon atom. 14) Atoms are made up of three fundamental particles as protons(1+), neutrons(0) and electrons(1-) as known as sub-atomic particles. In the centre of atoms is a tiny and dense region as nucleus where proton and neutron is and they stick tightly together with the about same mass. 15) In a normal atom there should be no charge because no. of protons = no. of electrons. Protons and neutrons have relative mass of 1; proton and electron have relative charge of +1 and -1. 16) Electrons occupied most place outside of nucleus and inside the atom.

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