sodium vs sodium carbonate

sodium

noun
  • Employing sodium. 

  • The chemical element (symbol Na) with an atomic number of 11 and atomic weight of 22.990. It is a soft, waxy, silvery, reactive alkali metal that is never found unbound in nature. 

sodium carbonate

noun
  • A salt, Na₂CO₃ formally derived from sodium hydroxide and carbonic acid; it is a white powder, soluble in water, with domestic, commercial and industrial uses; it occurs naturally as natrite 

How often have the words sodium and sodium carbonate occurred in a corpus of books? (source: Google Ngram Viewer )