History of the Periodic Table
Early Periodic Table
During the 19th century many scientists tried to find ways of classifying elements based on their properties and atomic weights.
In 1863 Newlands proposed his law of octaves which stated that similar properties were found every 8th element.
- He put the 56 elements into 7 groups according to their atomic weights.
- However their properties did not match well, meaning other scientists didnt accept his idea.
In 1869 Mendeleev produced a better table by leaving gaps for undiscovered elements.
- When some of the missing elements were discovered, they were found to have the properties predicted by Mendeleev, other scientist then accepted his idea.
- Mendeleev's table became the basis for the modern periodic table.
History of the periodic Table - Key Points
- When scientists arranged the elements in order of their atomic weight, the found similar properties at regular intervals.
- Mendeleev produced a table that became the basis for the modern periodic table.
- The early tables were based on atomic weights.
- 19th Century scientists knew nothing about protons and electrons.