Periodicity
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I have been give an assignment on periodic trends and I am looking for anomalies within the periodic table. Can you give me some guidelines on what these are?
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Corrie writes ....
Here are some more ideas from one of my colleagues, Jenkin, here at Re:act:
You might consider such things as the position of hydrogen and the differences in properties of the first member of a group compared with the others.
There are arguments for placing hydrogen in either Group 1, with the alkali metals, or in Group 7, with the Halogens. Think of such things as its electronic structure: only one electron, like group 1, or 1 electron short of a full shell, like group 7. Ionic and covalent compounds? Positive H+ and negative H- ions?
Differences between the first member of a group and the others: carbon’s unique chemistry, the different behaviour of lithium compounds on heating when compared with the corresponding sodium and potassium ones. This is a start, but you should be able to find other examples.
There are a few places where you can see that the sequence of elements in order of atomic number is not the same as if it were to be based on relative atomic mass; cobalt and nickel is one example, but there are others. There is a straightforward explanation of this, involving isotopes which you should be able to research yourself.
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updated: 21 February 2008
