Metals And Their Properties Physical and （金属和他们的物理属性）.pdfVIP

Metals And Their Properties- Physical and Chemical All the things around us are made of 100 or so elements. These elements were classified by Lavoisier in to metals and non-metals by studying their properties. The metals and non-metals differ in their properties. Main Group Al, Ga, In, Sn, Tl, Pb, Bi, Po. alkali elements Li, Na, K, Rb, Cs, Fr alkaline earth elements Be, Mg, Ca, Sr, Ba, Ra General Physical Properties of the metals  The metals have a shiny appearance, they show a metallic luster. Due to their shiny appearance they can be used in j ewellery and decorations. Particularly gold and silver are widely used for j ewellery. In the old days, mirrors were made of shiny metals like silver. Silver is a very good reflector. It reflects about 90% of the light falling on it. All modern mirrors contain a thin coating of metals.  Metals are mostly harder to cut. Their hardness varies from one metal to another. Some metals like sodium, potassium and magnesium are easy to cut.  Metals on being hammered can be beaten into thinner sheets. This property is called Malleability. Most metals are malleable. Gold and Silver metals are the most malleable metals. They can be hammered into very fine sheets. Thin aluminium foils are widely used for safe wrapping of medicines, chocolates and food material. 1  Wires are made from copper, aluminium, iron and magnesium. This property of drawing the metal in to thin wires is called ductility. Most metals are ductile.  Electric wires in our homes are made of aluminium and copper. They are good conductor of electricity. Electricity flows most easily through gold, silver, copper and