The Periodic Table
What is the Periodic Table
A table where all the elements in existence are arranged together in rows, in order of their atomic numbers is called the periodic table. Similar atomic numbers mean that the elements have similar atomic structure, thus similar chemical properties. The rows are known as periods and the columns are known as groups.
Usually, each row, or period, has the metal elements on the left, while the non-metals are on the right. Six of the groups are numbered, with the elements having their own group names as well, for example, the halogens are in group 17, and noble gases in group 18.
The periodic table was first developed and published by Russian chemist Dmitri Mendeleev, in 1869. It has since been extended with the discovery of new metals, with table remaining extremely useful in the field of chemistry as well as other scientific fields.
The Periodic Table of Elements
|Alkaline earth metals||Actinides|
The Lanthanide and Actinide Series
The lanthanides (atomic numbers 57 to 71) and actinides (atomic numbers 89 to 103) come in separate rows in the periodic table. The reason behind this can be stated simply as keeping them in the main table would make the periodic table too wide. You can see in following picture how the table would have looked with the lanthanides and actinides:
Now, this structure would make it difficult to handle the whole periodic table, especially on print, making in intelligible. So, keeping them in separate rows below solves the problem.