Astatine Chemical Properties (25 Facts You Should Know)

Astatine is one of the rarest occurring element present in the Earth’s crust. Astatine has few isotopic forms with short lifetime. Let us discuss more facts about astatine below.

Astatine is generally produced synthetically. It shows extreme radioactive nature making it unstable and difficult to synthesize as it vaporizes easily. The half lives are shorter than one second for most of the isotopes. It is classified as a non metal or metalloid.

Astatine has low vapor pressure and sublimes easily than iodine. Let us study more properties about astatine like atomic weight, mass number, CAS number, etc.

Astatine symbol

The atomic or chemical symbol of Astatine is At named after ‘astatos’, a Greek word for unstable form.

astatine logo
Atomic symbol of Astatine with atomic mass and atomic number on extreme top left and bottom left.

Astatine group in periodic table

The group that Astatine belongs to in a periodic table is 17. It belongs to a halogen family.

Astatine period in periodic table

Astatine belongs to the sixth period of a periodic table. It is the second last period in a periodic table.

Astatine block in periodic table

Astatine is a p-block element as observed from the periodic table due to the last electron entering p subshell.

Astatine atomic number

The atomic number of astatine is 85. Astatine has 85 positively charged protons in the nucleus and 85 electrons in the orbit.

Astatine atomic weight

The atomic weight of astatine is 210. Astatine has 125 neutrons calculated using Mass number-Atomic number = neutrons.

Astatine Electronegativity according to Pauling

The electronegativity of astatine according to Pauling scale is 2.2 lower than iodine and hydrogen as observed from the Pauling scale chart.

Astatine atomic Density

The atomic density of astatine is estimated to be around 8.91 to 8.95 g/cm3. It is extremely heavier than water due to its large size.

Astatine melting point

The melting point of astatine is 301.8 0C.  It is higher than iodine or radon.

Astatine boiling point

The boiling point of astatine is found to b 336.8 0C.  It is high as compared to other halogens due to its large size.

Astatine Van der Waals radius

The Van der Waals radius of astatine is calculated to be 200 pm (1pm = 10*-12) between the nuclei of two At atoms.

Astatine ionic/covalent radius

The ionic/covalent radius of astatine is not yet estimated or predicted due to its heavy form with low stability.

Astatine isotopes

Isotopes are chemical forms of the same element with same atomic number but different mass number. Let us check in details below for astatine.

The total number of isotopes observed for astatine are 3. They are listed below with their abundance and decay mode. They are unstable mostly.

Isotopes Abundance Decay mode
209At Synthetic α, β+
210At Synthetic α, β+
211At Synthetic α, ε
Isotopes, abundance and decay mode of Astatine element.

Astatine electronic shell

Electronic shell is a scientific representation of the distribution of the total number of electrons present in different orbits. Let us discuss in details below.

The electronic shell of astatine is 2, 8, 18, 32, 18, 7. The last electron enters 6p shell. It follows Hund’s rule and Aufbau principle.

Astatine energy of first ionization

The first ionization energy of astatine is found to be 899 kJ/mol for removing the only unpaired electron in the p subshell.

Astatine energy of second ionization

The second energy of astatine is not yet estimated as it achieves nearby stability after removing the only unpaired electron.

Astatine energy of third ionization

The third energy of ionization of astatine is not yet found.

Astatine oxidation states

The oxidation states shown by astatine are -1, +1, +3, +5, +7. -1 and +1 are mostly observed in astatine.

Astatine electron configurations

The electronic configuration of astatine is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p5.

Astatine CAS number

The CAS number of astatine is 7440-68-8 which is unique only for At.

Astatine ChemSpider ID

The ChemSpider ID of astatine is 142364-73-6. It can be used to find properties of At during database search.

Astatine allotropic forms

Allotropes are chemical forms of a substance with different chemical properties in the same physical state. Let us check if At has its allotropic forms.

The allotropic forms of astatine has not yet been found due to its radioactive nature, unstable form with short lifetime.

Astatine chemical classification

The chemical classification of astatine are listed below:

  • Astatine is a heavy element.
  • Astatine is a rare element.
  • Astatine belongs to halogen family.
  • Astatine is radioactive in nature.

Astatine state at room temperature

Astatine is found to be in solid state at room temperature as At is a heavier element with high density and all the atoms are packed tightly.

Is astatine paramagnetic?

Paramagnetism is a phenomenon when unpaired electrons are present in a material that aligns itself to the applied external magnetic field. Let us see if astatine is paramagnetic.

Astatine can be considered as a paramagnetic element due to the presence of one unpaired electron in the 6p subshell. The magnetic (moment) dipole vectors align itself to the direction of the external magnetic field.

Conclusion

Astatine is a radioactive element that belongs to halogen family with short lifetime. It is heavy and solid in state due to the presence of many electrons in the shells.