Talk:Nonmetal/Archive 3

Latest comment: 2 years ago by Double sharp in topic Astatine and Polonium
Archive 1Archive 2Archive 3Archive 4Archive 5Archive 9

Complementary pairs (follow-on from previous section)

Pairs again

More thoughts

The sub-sub sections below mostly relate to the paired comparisons. I’ve added some stuff to the first paragraphs of the group 17 and 18 sections. Feel free to copy edit and add refs. (Thanks for the wiki link, @ Sandbh!)

@YBG: Thanks for listing items of concern in an organised manner; @Double sharp: thanks for chiming in. --- Sandbh (talk) 05:34, 28 October 2023 (UTC)
NG/NM comparisons
Group 17/1 comparisons
Quote boxes
Metalloid outliers
Unclassified nonmetals

Lead section & paragraph length

Single distinguishing properties table

Restating YBG’s questions

Astatine and Polonium

Isn't astatine a metalloid (sometimes considered) ? I've even seen polonium considered a metalloid. 2603:6000:8740:54B1:98C0:1879:4C99:365D (talk) 02:08, 30 August 2023 (UTC)

Both have been classified as metalloids by some authors, though the consensus isn't as clear as for the main ones (B, Si, Ge, As, Sb, Te). See lists of metalloids for a more in-depth analysis. Complex/Rational 11:15, 30 August 2023 (UTC)
Thanks. I've usually seen astatine regarded as a nonmetal or metalloid; occasionally as a metal. Polonium I've seen regarded as a metalloid, though usually a metal. 2600:1008:B18F:94F7:495F:FB73:818D:885A (talk) 17:53, 31 August 2023 (UTC)

Astatine has an unusual history in that when it was first syntheized it was considered to be a metal. Experimental evidence and recent theory suggests it may indeed be a metal. In-between it seems to have suffered from its association with the halogens. Ergo it must be a nonmetal, ignoring trends of increased metallicity going down the group. Non-relativitic calcuations pointed to it being a semiconductor and hence a metalloid candidate. Relativity points to it being a post-transition metal.

Polonium is soluble in acids, forming the rose-coloured Po2+ cation and displacing hydrogen: Po + 2 H+ → Po2+ + H2. It has no band gap and no semiconducting allotropes. Hence it's a metal. Sandbh (talk) 05:46, 19 September 2023 (UTC)

Polonium is further down in the electrochemical series than hydrogen, and appears in about the same place as ruthenium. Hence, a caveat must be added: polonium often gets oxidised by media that electrochemically should not oxidise it, because of radiolytic decay products. Double sharp (talk) 15:37, 12 January 2024 (UTC)