H₂O vs hydrogen oxide

H₂O

noun
  • Water as a chemical substance. 

  • Hishammuddin Hussein Onn, Malaysian politician and son of Hussein Onn, third prime minister of Malaysia. 

hydrogen oxide

noun
  • The simple systematic name for water, H₂O. 

How often have the words H₂O and hydrogen oxide occurred in a corpus of books? (source: Google Ngram Viewer )