The History of the Periodic Table
Chemistry: AQA GCSE Higher, topic 1.1.19
History of the Periodic Table
Before scientists discovered sub-atomic particles (protons, neutrons and electrons), they tried to sort elements by their mass. Today, we rank elements by their atomic number (the number of protons in an atom's nucleus).
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Newlands' periodic table
- John Newlands was the first chemist to devise a periodic table.
- Newlands' periodic table was ordered by the mass of the element.
- But, the table was incomplete, and some elements were placed in inappropriate groups.
Mendeleev's periodic table
- Dmitri Mendeleev recognised that there may be undiscovered elements.
- Mendeleev added gaps to Newlands’ table to account for undiscovered elements.
- Mendeleev even predicted the properties and masses of these undiscovered elements!
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The modern periodic table
- The discovery of protons and isotopes has shown that Mendeleev ordered elements exactly by relative atomic mass.
- Therefore, the modern periodic table looks very similar to Mendeleev's (except the gaps are filled).
Test yourself on The History of the Periodic Table
What discovery proved Mendeleev's periodic table to be correct and Newlands' to be wrong?
Which two scientists were the main influencers of the modern periodic table?
How did Dmitri Mendeleev revolutionise the periodic table?