Metals are elements or alloy in chemistry. These metals are classified by their property of being a good heat and electrical conductor. In a metal the electrons are lost to form anions. These anions are surrounded by un-localized electrons, and these electrons are responsible for the property of conductivity. Chemical elements vary due to their different chemical and physical properties, so every group of elements have different physical and chemical properties. Metals also have different properties as compared to other elements. Metals have high thermal (heat) conductivity, electric conductivity, luster and density. Metals are a group there are many elements in the group of metal. There are many metals which have different property with the other metals. Some have low density and low melting and boiling points. Many metals are extremely reactive, they react with sunlight, air and other materials or chemical. That's why you see roughness and rust on some metals but on some is fine and clear although they are used for the same purpose.