Changes

: Once the structure of the [[atom]] was investigated by physicists in the early 1900s it was discovered how to correct '''Mendeleev's Periodic Table'''by ordering the [[element]]s by [[Atomic Number]] instead of [[Relative Atomic Mass]]. This produced the modern [[Periodic Table]].

{{#ev:youtube|https://www.youtube.com/watch?v=O-48znAg7VE}}