Asked in Oxidation Numbers
Why astatine have different oxidation number?
Different from what? Very little is known about the chemistry of astatine - it is radioactive and the most stable isotope has a half life of 7-8 hrs! As far as is known and that isn't far- astatine is most like iodine with ONs presumably of -1, 1, 3, 5, 7 ...
Astatine has 85 protons what is the atomic number?
The atomic number is the number of protons, so the atomic number of astatine is 85. ...