table of elements
Table created by Dmitry Mendeleyev in 1869 that classifies the now approximately 110 known chemical elements such as oxygen, hydrogen, iron and lead. The elements are classified in order of their atomic weight and arranged into groups having similar properties.
symbol 
The name of each chemical element is represented by one or two letters, the first of which is in uppercase (e.g., O for oxygen, Cl for chlorine).