Elasticity is the ability of an object to return to its original size or shape when external forces are removed. Strength is the ability of a solid to withstand a load without failure. There are four properties which are derived from these characteristics. The tensile strength of a material is the force per unit cross-sectional area applied perpendicularly to the cross section that is required to break a rod or wire of that material. Tensile strength is a measure of cohesion between adjacent molecules over the entire cross sectional area.
Malleability is the extent to which a solid can be hammered or rolled into sheets.
Ductility and malleability are high in most metals, but low in other solids. Some metals that are highly malleable and highly ductile are silver, gold, platinum, copper, aluminum, and iron. In the process of hammering, rolling, or drawing, layers of atoms of a metal are forced to slide over one another, thus changing their positions in the crystal pattern. The cohesive forces are strong, and molecules of the material do not become widely separated from each other during their rearrangement, hence keeping the metal together while its shape is being changed. The ability of an object to return to its original size or shape when external forces are removed is described as its elasticity .