Thursday, May 22, 2008

HYDROGEN is in the wrong place in the periodic table,how did this happen?

Hydrogen is shown in the wrong position (as a Group 1 element) on the Periodic Table of Elements. Hydrogen is a halogen (Group 17). This page is an exploration of how this misplacement could have happened and gone uncorrected for decades. Click here to see the actual arguments that hydrogen should be classified as a halogen and is therefore in the wrong position within the current 'modern' Periodic Table of Elements.
In the mid-1800's, about 60 elements were recognized and different scientists started trying to find ways to organize them according to both the size of their atoms and the similarities between properties they displayed. Today's Periodic Table of Elements emerged from these efforts.
The best webpage I found with information about the origins and history of the Periodic Table of Elements and it's development can be viewed at http://mooni.fccj.org/~ethall/period/period.htm. It is very well done, both informative and entertaining.
The most useful general arrangement turns out to be a Cartesian grid. Each row represents the elements possible in an electron shell (two elements for the first row, eight elements for the second row, etc). Each column is organized either by the number of electrons in the outer shell OR the number of electrons MISSING from the outer shell.
It's fairly easy to see how the misplacement of hydrogen could have happened in the first place with our left-to-right cultural thinking.
Group One, the left-most column in the Periodic Table, is made up of elements with a single electron in their outer shell. This is the 'first' column and since hydrogen fits this rule, it was very logically positioned at the top of this group.
However, as one begins filling in the elements from left to right in the table, it immediately becomes apparent that most of the columns (groups) should be determined by the number of electrons MISSING from the outer shell. This is usually more important in determining an element's 'similarity of properties' to other elements.
So most of the table needed to be arranged according to the number of electrons missing from the outer shell (from right to left) which it was. One can easily see this simply by looking at the current Periodic Table. Most of the columns are aligned to the right (based on the number of electrons missing and counting up from right to left).
For example, the right-most column (Group 18) consists of elements with zero electrons missing from their outer shells. Their properties are quite unique. They are all gases and all inert which means they won't normally bond with other elements.
This is because all the electron shells are full. They don't 'want to' give up any electrons and they don't have room for any more. This is the most obvious 'group' of elements in the periodic table based on like properties. However, this group was one of the last to be discovered (early 1900's). My guess is that the modern Periodic Table filled out quickly from right to left once the inert gases were added.
The next two most obvious groups, based on like properties, are the alkali metals (Group 1) and halogens (Group 17). These two groups have one electron in their outer shell and one electron missing from their outer shell respectively. They are very active meaning that they bond readily with other elements (especially with each other) because of the free or missing electron. Almost opposite to their neighbor, the inert gas group.
It turns out that if an element has only one electron (alkali metals) or two electrons (alkaline earth metals) in its outer shell, it has some unique similarities to other elements in the same category (same number of electrons in the outer shell), so the left two columns in the periodic table are accurate and useful (for the most part).
Hydrogen has the unique property that it fits into two of the Periodic Table's Groups having both one electron in its outer shell AND one electron missing from its outer shell. It doesn't have to be in Group One. In fact, it fits MUCH better in Group 17. So can anyone please tell me why it is still positioned with alkali metals instead of halogens in the current 'modern' Periodic Table? Are we truly THAT unable to 'think outside the box' as a species?

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