History of the Periodic Table

My Knowledge

The Beginning

The most important part of the discovery of the Periodic Table was the discovery of the individual elements. Even though elements such as gold, silver, tin, mercury, lead and copper has been known for years, the first real scientific discovery of an element was in 1649 when Henning Brand discovered Phosphorous.

Over the next 200 years after the discovery of Phosphorous, Chemists found a huge amount of information on compounds and the properties of elements.

By the year 1869 there was 63 elements discovered. Scientists than began to develop classifications for the elements.

The Periodic Table

By 1869 Dmitri Mendeleev had created the first ever Periodic Table according to Atomic Mass. The other attempts before Mendeleev had only organized the elements according to their properties, however, Mendeleev is generally accepted as the creator of the Periodic Table.

With the information he gathered, he was able to see the elements he was missing which hadn't been discovered yet. After understanding the patterns of the Periodic Table, Mendeleev was able to predict the elements appearance, melting point, atomic mass, density and formula of chloride.

Throughout the years other scientists were able to fill in the missing elements. They also ordered the elements by atomic number instead of atomic mass. Henry Moseley was the firs to order the elements by atomic number so the elements would fit better in 1913.


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Common Knowledge about the Periodic Table

The main 3 classifications of the Periodic Table are the metals, non-metals and Metalloids.
All the metals are together, starting from Lithium and ending at Polonium. These metals are solid, shiny (good conductors of heat), malleable and ductile.
The Non-Metals are on the right side of the periodic table (along with Hydrogen). These are the complete opposite to the metal properties.
The Metalloids are the elements which are on the border with the Metals. The properties of the Metalloids are a cross between Metals and Non-Metals.

There are also groups and periods on the Periodic Table. The groups go vertical whilst the periods go horizontal. What is important about the groups and periods is that they tell us special information such as, the groups tell us how many valence electrons there is on the outer later of a element, whilst the periods tell us how many orbit shells there will be in an element.


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