{"id":196,"date":"2020-04-09T09:50:14","date_gmt":"2020-04-09T09:50:14","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=196"},"modified":"2023-08-15T15:09:11","modified_gmt":"2023-08-15T15:09:11","slug":"astatine","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/astatine\/","title":{"rendered":"Astatine (At)"},"content":{"rendered":"\n

Astatine is a radioactive chemical element with an atomic number 85 in the periodic table of elements<\/a>. The total amount of astatine found naturally in the Earth\u2019s crust is almost 25 grams at any given time, which makes astatine the rarest chemical element on Earth. Being a member of the family of halogen elements in the periodic table, the outer shell of astatine comprises seven valence electrons.<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Astatine<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>At<\/td><\/tr>
Name<\/td>Astatine<\/td><\/tr>
Atomic number<\/td>85<\/td><\/tr>
Group<\/td>Halogen (Group 17)<\/td><\/tr>
Period<\/td>6<\/td><\/tr>
Crystal Structure<\/td>Unknown<\/td><\/tr>
Atomic weight (mass)<\/td>209.9871 [210 – average]<\/td><\/tr>
Shells<\/td>2,8,18,32,18,7<\/td><\/tr>
Orbitals<\/td>[Xe] 4f14 5d10 6s2 6p5<\/td><\/tr>
Valence<\/td>1,3,5,7<\/td><\/tr>
Color<\/td>A shiny dark-colored chemical element<\/td><\/tr>
Physical state<\/td>Solid metal at room temperature<\/td><\/tr>
Half-life<\/td>From less than 0.90(25) milliseconds to 58 minutes<\/td><\/tr>
Electronegativity according to Pauling<\/td>2.2<\/td><\/tr>
Covalent Radius<\/td>1.45 \u00c5<\/td><\/tr>
Atomic Radius<\/td>1.43 \u00c5<\/td><\/tr>
Ionic Radius<\/td>—<\/td><\/tr>
Van der Waals radius<\/td>200 pm<\/td><\/tr>
Melting point<\/td>302\u00b0C<\/td><\/tr>
Boiling point<\/td>337\u00b0C (estimation)<\/td><\/tr>
Density<\/td>No data available<\/td><\/tr>
Name Origin<\/td>Greek: astatos (unstable)<\/td><\/tr>
Discovery By<\/td>D.R.Corson, K.R.MacKenzie, E.Segr\u00e9<\/td><\/tr>
Year<\/td>1940<\/td><\/tr>
Location<\/td>United States<\/td><\/tr>
Pronunciation<\/td>AS-teh-teen<\/td><\/tr>
Oxidation States<\/td>(\u00b11),3,5,7<\/td><\/tr>
Uses<\/td>Since its isotopes have such short half-lives there are no commercially significant compounds of astatine.<\/td><\/tr>
Description<\/td>Colorless, odorless, tasteless, radioactive, heavy, noble gas<\/a>.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

With the periodic table symbol At, the atomic mass of 209.9871 g.mol -1, and electronic configuration [Xe] 4f<\/span>14<\/span>5d<\/span>10<\/span>6s<\/span>2<\/span>6p<\/span>5<\/span>, \u0430statine reaches its (estimated) boiling point at 337\u00b0C with probable valences of 1, 3, 5, or 7, while the melting point is achieved at 302\u00b0C. Both melting and boiling points of astatine increase with the atomic number. This member of the halogen family of elements in the periodic table has an electronegativity of 2.2, according to Pauling, whereas the atomic radius according to van der Waals is 200 pm.<\/span><\/p>\n\n\n\n

The chemical properties of astatine also include:<\/span><\/p>\n\n\n\n