Period 6 element between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods). Lanthanum is a chemical element with the symbol La and atomic number 57. It is the first element in the lanthanide series. It is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series,
Pewter known as "trifling metal" or "trifle", was used for holloware and is made up of fine metal with approximately 4% lead. The last type of pewter, known as "lay" or "ley" metal, was used for items that were not in contact with food or drink. It consisted of tin with 15% lead. These three alloys were used with little variation until the 20th century. Older pewters with higher lead content are heavier, tarnish faster, and oxidation gives them a darker silver-gray color. Pewters containing lead are no longer used in items that will come in contact with the human body