Science Periodic Table Help?

Question

At the bottom of the periodic table it has an extra two rows. Sometimes these can be put into the table but most times they are presented below. Why are they down there? Why are they not connected to the rest of the table? What makes them so different? Why are there two rows? What separates them from the group, then separates them again?

So why are the two rows separate from the group?
Why are they separated again?

Most detail wins!
Please i need lots of information, so if they are part of a special grouping (row one is part of (i don't know) further explain that grouping (row one is part of (i don't know) which is separated because it fits a ....) and so on until it links back to being apart of the main table!

Answer 1

The lanthanide series was put below the main table when the chemists found that members of the series were so chemically similar that they seemed to all belong in the same space in the table (the space for lanthanum, the first member). The actinide series was found to behave the same way: it was as if they all belonged in actinium's spot.



Since, in a flat table, they couldn't stack the boxes for these very similar elements, they put the sets of boxes in separate places below the table.

Glenn Seaborg proposed a modified table that included these series within it; an example can be seen at http://en.wikipedia.org/wiki/Periodic_table_(wide) .

Answer 2

Mendeleev's periodic table was based on law of octaves as at the time of initial classification and available knowledge about elements it was observed that when elements were arranged in the order of increasing atomic weight the eight element resembled the first.Mandel eve made certain corrections on the basis of similarities and corrected some atomic weights and was also able to point outexistencee of certain new elements.With advent of atomic number the periodic table was based in order of increasing atomic numbers and the elements were classified in eight groups.With increasingknowledgee and information elements were placed in sub group A and B.Atomic structure studies and showed that electrons withincreasingn atomic numbers follow a set pattern and it was found that they go into s,p d and f orbitals.Elements with filling of s and p orbitals are placed in sub group A and those with filling of d orbitalsin sub group B. In case of elements where electrons aregoingg to fill the f orbitals resemble one element that they needed to be groupedtogetherr and could not be placed/adjusted in theexistingg design so they were placed below in seprate period and also giving place to 14 elements in one sub group in normal scheme . These elements are called lanthnides and actinide,In the modern periodic table is desigined in spirial form to give them proper regular place.These two rows of elemnts are called inner transition elemnets.If you study certain physical properties from the periodic table, you will notice pecularities and understand the specail status of these elemts.

Answer 3

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