The Friday File: This week, the Periodic Table celebrates its 150th birthday. In 1789, Antoine-Laurent de Lavoisier (who was beheaded in 1794) first published a list of 33 elements thought to be incapable of being broken down. However, it was Dimitri Mendeleev in 1869 who first organized the 63 then-known elements by their atomic weights and in columns that shared chemical and physical properties. HS students have suffered ever since.
