[Winga]

Is it metal or metalloid?

From the fourm's periodic table, it is metalloid, but from the website webelements.com, it is metallic.

According to IUPAC, which one is correct?

[AWK]

Both terms are good enough since there is no unique way of distinguishing a metalloid from a true metal, but the most common is that metalloids are usually semiconductors rather than conductors.

[jdurg]

That's not true.  Metalloids have pretty distinguishing characteristics as opposed to true metals.  A metal will conduct electricity quite easily while a metalloid will only partially conduct it.  (Semiconductors).  Metalloids are very brittle, crystalline substances while metals tend to be much less brittle.  (I.E. you can take a hammer to a solid piece of zinc and it's not going to shatter into a million tiny shards.  Take a hammer to a solid piece of silicon or antimony and the whole thing will seemingly explode like glass).  Again, metals are malleable substances while metalloids most definitely are not.  (Malleable meaning that they can be beaten into shapes and specific designs.  Metalloids, like non-metals, have to be cast into shapes).  Metalloids also don't seem to exhibit a lot of metallic bonding within their own pure forms.  The only real reason they are called 'metalloids' is because in many cases they look like metals and exhibit a tiny bit of metallic bonding.  In reality, they are more like non-metals than they are metals.

For polonium, i'm not sure what it is.  I don't know if they've ever made enough of it to see it in a bulk form whereby they could investigate its physical properties.  Its half-life is only 138 days so you really wouldn't want to have a massive sample of it around without some pretty serious protection.

[Mitch]

Where does it say that on webelements?

[jdurg]

Where does it say that on webelements?

The main page for Polonium on webelements lists it as a metal near the top of the page.

[Mitch]

a metallic chalcogen, go figure.

[AWK]

Jdurg precisely pointed out the difference between metals and metalloids.
In the public document of US Atomic Energy Commision and National Academy of Science "The Radiochemistry of Polonium" from 1961 this element is classified as metallic element, but no data of electric conductivity is given.
This is a small excerpt from this document: "Polonium is a silvery gray in color, and is soft enough to be scratched readily."

[Winga]

a metallic chalcogen, go figure.

Therfore, we should not classify the elements as metallic, semi-metallic or non-metallic, but using the new terms, such as pnictogens and chalcogens, right?

[jdurg]

The problem with Polonium is that its radioactivity is so high in energy that it is literally 'hot'.  I believe I read somewhere that a gram of pure polonium would have a temperature of 500C due to its radioactivity.