The Naked Scientists

The Naked Scientists Forum

Author Topic: Why are the actinides not in the main part of the Periodic Table?  (Read 1021 times)

Offline Sai Tanishq Nannapaneni

  • First timers
  • *
  • Posts: 2
    • View Profile
Hi people. I have doubt on periodic table especially on arrangment of radio active elements and the elements of the 7th period dont have the same properties as that to which group they belong to and the new elements are possible in near future so where we gone place the elements and a new period (i.e8th)should be formed if that is the case then table becomes lenghty. Is there any alternative i mean we have to palce these radioactive elements in seperate table from the periodic table.If so i have a design ...if u find any find any mistake in my above theroy can please reply me.If u reply me there is no such amistake i would send my design to you.
 
« Last Edit: 02/06/2016 08:31:06 by chris »


 

Offline chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1880
  • Thanked: 145 times
    • View Profile
In what way do you think the 7th period elements don't have the same properties as the group they belong in? Do you mean chemical properties?

Certainly there are some deviations that will appear with heavier elements, that are not apparent with the lighter elements. For instance, relativistic effects begin to be significant for elements in the 6th period. This doesn't change the valence of any of the elements (for instance, Hg still reacts similarly to Cd), but does change the trends in electronegativity, ionic radius etc.
 
The following users thanked this post: Sai Tanishq Nannapaneni

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8676
  • Thanked: 42 times
    • View Profile
As you go to heavier and heavier transuranic elements the half lives get shorter.
For the 7th period, a lot of the "chemistry" is already very uncertain because the elements don't last long enough to check.
https://en.wikipedia.org/wiki/Flerovium#Experimental_chemistry
How do you plan to check what the elements of the 8th row do?
How do you plan to show that the current periodic table is "wrong"?
 
The following users thanked this post: Sai Tanishq Nannapaneni

Offline Sai Tanishq Nannapaneni

  • First timers
  • *
  • Posts: 2
    • View Profile
 I am trying to replace the actinides from the existing periodic table because they don't follow the order of other elements in the table. Why to place this elements only in one table as 118 element has reactivity but placed in noble gas group.perhaps this group doesn't show reactivity by the physical term.So if a novice is trying to learn the table he gets confused by the above thing which I have explained.In future we don't know that there is a possibility of new elements around (184) predicted which may make the table lengthy and confusable.so, my aim is to make a new table for this radio active elements.Not touching the other elements in table.If it's ok then I have a theory written.i will be forwarding it here.
Thank you
 

Offline chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1880
  • Thanked: 145 times
    • View Profile
the above thing which I have explained.


I still don't understand what you are explaining. How are the actinides different from what is implied in the periodic table?
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4131
  • Thanked: 249 times
    • View Profile
Quote from: Sai Tanishq Nannapaneni
Why are the actinides not in the main part of the Periodic Table?
In a conventional periodic table, the Actinide row (and Lanthanide row) are presented as a separate table below the main table.

But this is just a layout trick to reduce the width of the table. The chemical properties of the Actinides are somewhat like their namesake Actinium, and the whole row should actually fit where the single element Actinium resides.

The Wikipedia shows the Actinides in their correct position, with an extra-wide periodic table.
https://en.wikipedia.org/wiki/Actinide

Quote
Is there any alternative?

Apparently, Mendeleev came to his layout by carrying a deck of cards, each with the characteristics of one element. He kept dealing them out in different arrangements until he came up with one that made sense to him - basically the one we use today (with a few "holes" for elements which were unknown at the time).

But there have been many alternative layouts proposed for the periodic table, including some three-dimensional ones!
You can see some examples here: https://en.wikipedia.org/wiki/Alternative_periodic_tables

If you have a new layout, please post a picture of it in this thread, and I'm sure some of the chemists here can give you some feedback.
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums