Astatine At (Element 85) of Periodic Table

85 At (Astatine)

Appearance:  Unknown, (Probably metallic)

Mass number:  210

Atomic weight:  209.9871 g/mol

Atomic number (Z):  85

Electrons:  85

Protons:  85

Neutrons:  125

Group:  17

Period:  6

Block:  P

Element category:  Halogen

Electrons per shell:  K2, L8, M18, N32, O18, P7

Electron configuration:  1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p5

Phase:  Solid

Melting point:  575 K (302 oC)

Boiling point:  610 K (337 oC)

Density:  6.35±0.15 g/cm3

Half Life(s):  29000

Lifetime(s):  42000

Decay mode:  β+ decay

Molar volume:  32.94 cm3/mol

Heat of fusion:  6 kJ/mol

Heat of vaporization:  54.39 kJ/mol

Oxidation states:  -1, +1, +3, +5, +7

Ion charge:  At

Electronegativity: Pauling scale: 2.2

Valence: 7

Electron affinity:  279.1 kJ/mol

Ionization energies:  1st: 899.003 kJ/mol

Covalent radius:  150 pm

Vander waals radius:  202 pm

Crystal structure:  Face centered cubic

Thermal conductivity:  1.7 W/(m.K)

CAS Number:  7440-68-8

Naming:  After Greek Astatos (Meaning ‘Unstable’)

Discovery: Dale R. Corson, Kenneth Ross MacKenzie, Emilio Segre (1940)

Isotopes:  209At 210At 211At

Uses:  Currently no uses for astatine outside of research.

Biological role:  It is toxic due to its dangerous radioactivity

Natural abundance:  Astatine-211 is made in nuclear reactors by the neutron bombardment of bismuth-200.


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