// todo need optimize like in event.jsp. Add indexing or not indexing this page. Many scientists found that triads (chemical relationships expanded beyond the triad). (1 janv. 1829 – 1 janv. 1858) (La bande de temps)

Many scientists found that triads (chemical relationships expanded beyond the triad). (1 janv. 1829 – 1 janv. 1858)

Description:

During this time fluorine was added
to the halogen group; oxygen, sulfur,selenium and tellurium were grouped into a family while nitrogen,
phosphorus, arsenic, antimony, and bismuth were classified as another.