[DOC] [TLE] Astatine - Wikipedia [PAR] Astatine is a radioactive chemical element with the chemical symbol At and 
atomic number 85, and is the rarest naturally occurring element on the Earth's 
crust. It occurs on Earth as the decay product of various heavier elements. All its 
isotopes are short-lived; the most stable is astatine-210, with a half-life ... Astatine 
is an extremely radioactive element; all its isotopes have short... [DOC] [TLE] Astatine, Chemical Element - uses, elements, metal, number, name ... [PAR] All isotopes of astatine are radioactive and decay into other elements. ... What is 
known is that it has properties similar to those of the other halogens fluorine, 
chlorine, bromine, ... evidence of element 85 at the end of an experiment they 
were conducting with a cyclotron. ... These isotopes have half lives of 5.5 to 8.3 
hours. [DOC] [TLE] Halogen elements facts, information, pictures | Encyclopedia.com ... [PAR] Get information, facts, and pictures about Halogen elements at Encyclopedia.com
. ... They are listed below, along with chemical symbol and atomic number: 
Fluorine (F) 9; Chlorine (Cl): 17; Bromine (Br): 35; Iodine (I): 53; Astatine (At): 85 
..... 20 known isotopes is stable, and the longest-lived has a half-life of only 8.3 
hours. [DOC] [TLE] astatine (At) | chemical element | Britannica.com [PAR] At radioactive chemical element and the heaviest member of the halogen 
elements, ... Astatine, which has no stable isotopes, was first synthetically. ... in 
which they occur by minor branching (astatine-218 in the uranium series, ... 
Because of the short half-lives of astatine isotopes, only very small quantities ... 
See All Stories. [DOC] [TLE] Halogens - Astatine - Atoms, Nucleus, Isotope, and Radioactive ... [PAR] All isotopes, atoms with the same number of protons in the nucleus and different 
numbers ... Most of its identified isotopes have half-lives of less than one minute. [DOC] [TLE] The Chemistry of the Halogens [PAR] They all form diatomic molecules (H2, F2, Cl2, Br2, I2, and At2), for example, and 
they ... (The most stable isotopes of astatine have half-lives of less than a minute. 
..... Iodine is the only halogen that forms an XY7 interhalogen compound, and it... [DOC] [TLE] 7A - Halogens - Angelo State University [PAR] Since all of the halogens have one unpaired electron in their atomic forms, it is 
easy ... The X2 molecules are nonpolar, so the only interactions between them 
are fairly ... They are usually found in combination with various metals in minerals
, or in .... all of its isotopes have fairly short half-lives (the longest, astatine-210, 
has a... [DOC] [TLE] Group 17: General Properties of Halogens - Chemistry LibreTexts [PAR] Aug 18, 2015 ... Although astatine is radioactive and only has short-lived isotopes, ... Because the 
halogen elements have seven valence electrons, they only require one ... All 
halogens form Group 1 salts with similar properties. .... In addition, astatine has a 
very short radioactive half-life, no longer than a couple of hours. [DOC] [TLE] A Tale of 7 Elements: Element 85Astatine [Excerpt] - Scientific ... [PAR] Jul 5, 2013 ... The identity of the "discoverer" of this halogen element very much ... and Shawn 
Burdette, whose 2010 article I have drawn heavily from. ... They also took this 
decay to indicate the presence of element 85 in ... First of all, they state that: .... 
The isotope is an  particle emitter with a convenient half-life of 7.2... [DOC] [TLE] Condensed Astatine - Roald Hoffmann [PAR] Sep 12, 2013 ... The half-lives t1=2 of the unstable astatine isotopes, which span the mass ..... 
also the only halogen that is metallic at all higher pressures. [DOC] [TLE] Condensed Astatine: Monatomic and Metallic - School of Physics ... [PAR] Sep 12, 2013 ... The half-lives t1=2 of the unstable astatine isotopes, which span the mass ..... 
also the only

Question: Astatine is the only halogen whose isotopes are all this, which is why they have half-lives
Answer: radioactive