Metals also have considerable elasticity. A metal spring can be stretched, for example, but when the load is removed, it contracts to its original length. The electronic structure of metals explains many of their properties. In metals the outermost shell of the atom is generally not filled with all the electrons it can hold. Thus when many atoms come together to form a solid metal, the electrons in the outermost shells are shared among neighboring atoms and move freely from one atom's shell to another.
Heat is a phenomenon involving whole atoms.
In solid metals the atoms are arranged in a regular structure. When the metal is heated, the atoms vibrate, influencing their neighbors to vibrate as well. Metals are malleable and ductile because sheets of these atoms can slip gradually past one another. Metallurgy Separating metals from their ores, purifying and working the metals into usable forms, and understanding the physical nature of metals are all aspects of metallurgy. The field is loosely divided into process metallurgy, which involves the extraction and processing of metals, and physical metallurgy, which is concerned with the study of the physical properties and mechanical behavior of metals.