Scientifically, are Polonium (Po) and Astatine (At) metalloids?

Question

at 273K...

Answer 1

The latest thinking is "no".  The current interpretation of metalloid does not include At or Po.   Astatine was never a metalloid, and polonium has been included and is now excluded from that list even though it touches the "stair-step" line.  

The elements that ARE metalloids are B, Si, Ge, As, Sb and Te.

You will find polonium listed both ways in the literature.  It really doesn't make much difference since there is so little polonium in the Earth's crust and even if you had a sample you couldn't pass it on to your grandchildren because the most stable isotope has a half-life of 103 years and much of it would be lead.

So list polonium as either a metalloid or not.  You will be right either way.

Answer 2

Polonium is a metalloid, almost a metal.  Astatine is still probably a non-metal.  

Answer 3

The term "metalloid" may sound like a reference to a heavy-metal music fan, but in fact it describes a small collection of elements on the right-hand side of the periodic table. Forming a diagonal between boron and astatine, which lies four rows down and four columns to the right of boron, the metalloids are six elements that display qualities of both metals and nonmetals. (Some classifications include boron and astatine as well, but in this book, they are treated as a nonmetal and a halogen respectively.) Of these six—silicon, germanium, arsenic, antimony, tellurium, and polonium—only a few are household names. People know that arsenic is poison, and they have some general sense that silicon is important in surgical implants. But most people do not know that silicon, also the principal material in sand and glass, is the second-most plentiful element on Earth. Without silicon, from which computer chips are made, our computer-based society simply could not exist.

Answer 4

Astatine is a halogen, I think Polonium is a heavy metal.

Answer 5

The short answer is SORT OF.

Metalloids have properties of both metals and non-metals.

They are the elements found along a stair-step line separating metals from non-metals. According to one definition, this line is drawn from between Boron and Aluminum to the border between Polonium and Astatine. However, depending on the criteria chosen, both elements 84(Po 209) and 85 (At210) can be considered metalloids. Some listings exclude Po and At, while others (as above) exclude only At.

That polonium was considered metallic is evident from its "ium" ending. Astatine is the only radioactive halogen and like iodine, is a solid. It is considered to be "more metallic" than iodine, However, since it is the rarest element existing in nature (about one teaspoonful in all of the Earth), it is more of a "manufactured" element, being made by bombarding bismuth with energetic alpha particles to obtain relatively long-lived 209At - 211At, which can then be distilled from the target by heating in the presence of air.

Answer 6

Polonium is a metal (and incredibly poisonous!)

Astatine is described in several sources (e.e webelements) as semi-metallic.