Periodic table 

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© Royal Society of Chemistry 2014 - we do not own the rights to this image
The royal society of chemistry has available this amazing interactive periodic table. The table allows you to click on each individual element providing a variety of information including the use of pictures, videos and data trends. It is one of the best known interactive periodic tables on the internet.

History
The periodic table was credited to Dimitri Mendeleev a Russian chemist who had the first version of the periodic table published; however, many other chemists had put forward their own versions of the periodic table and what they believed it should be like. Julius Lothar Meyer was one of the chemists who also published their table, but it was Mendeleev’s idea that was accepted, this was due to two major reasons: first being he left gaps in the periodic table for not yet discovered elements (this was done before but Mendeleev had given order and identified particular trends in patterns); secondly, he did not arrange the elements according to their atomic masses, but on their chemical properties, this proved later on that his concept had listed the elements in order of their increasing atomic numbers. His periodic table identified trends in the different elements that were discovered at that time. Mendeleev was able to place the elements into groups (shown in columns) which was basis of the modern periodic table that we see today.
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Dmitri Mendeleev in 1897
Groups and periods
The periodic table is made up of columns called groups; horizontal lines called periods and different regions of the table known as blocks. The groups are responsible for more significant trends than periods; within the same groups there are present the same electronic configurations in their outer most shell. This is one of the main reasons as to why a group with the same number of outermost electrons will have similar chemical properties; for example the halogens (group 7) have seven electrons in their outer shell, they are all so determined to accept an electron to complete their outer shell. This allows the elements within group 7 to show similar properties.


  • Groups - Columns in the periodic table, the elements in a group show similar properties and are responsible for identical trends.
  • Periods - Are the horizontal lines across the periodic table, they also represent the number of shells an element has, for example a period 2 element will have 2 shells. 
  • Blocks - There are in theory 5 differnet blocks in the periodic table:
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s-block,
p-block,
 d-block,
f-block
and g - block
However the latter of the block (g-block) is part of the periodic table which is not talked about too often.
The block themsleves are categorized via the arrangement of electrons in "subshell" orbitals.

Periodic tables available on the internet

The Royal society of chemistry has in my opinion one of the best interactive periodic tables out there; however there are plenty of other periodic tables which are just fantastic.
Check out these links below:



1) Dynamic Periodic Table
This periodic table is great it's a Interactive periodic table with dynamic layouts showing names, electrons, oxidation, trend visualization, orbitals, isotopes, and compound search.



2) WebElements Periodic Table
By clicking on a single element it allows you to have a look at general properties, data, history and uses.



3) TED-Ed - Periodic table
This periodic table has a great interactive advantage as each element has to go with it a video which discusses the details associated with that element.