Template:Infobox thallium

{{Infobox element

|symbol =Tl

|Z =81

|number =81

|name =thallium

|abundance=

|abundance in earth's crust=

|abundance in oceans=

|abundance in solar system=

|left=mercury

|right=lead

|above=In

|below=Nh

|image name=Thallium pieces in ampoule.jpg

|appearance=silvery white

|electrons per shell=2, 8, 18, 32, 18, 3

|phase=

|density=11.873 g/cm³

|density conditions=(at 20° C)

|density gpcm3mp=11.22

|melting point K=577

|melting point C=304

|melting point F=579

|boiling point K=1746

|boiling point C=1473

|boiling point F=2683

|heat fusion=4.14

|heat vaporization=165

|heat capacity=26.32

|vapor pressure 1=882

|vapor pressure 10=977

|vapor pressure 100=1097

|vapor pressure 1 k=1252

|vapor pressure 10 k=1461

|vapor pressure 100 k=1758

|vapor pressure comment=

|crystal structure=hexagonal close packed

|crystal structure Pearson symbol=hP2

|lattice constants=a = 345.66 pm
c = 552.52 pm (at 20 °C){{cite book |last=Arblaster |first= John W. |title=Selected Values of the Crystallographic Properties of Elements |publisher=ASM International |publication-place=Materials Park, Ohio |date=2018 |isbn=978-1-62708-155-9}}

|electronegativity=1.62

|number of ionization energies=3

|ionization energy 1=589.4

|ionization energy 2=1971

|ionization energy 3=2878

|atomic radius=170

|covalent radius=145±7

|Van der Waals radius=196

|magnetic ordering=diamagnetic

|magnetic ordering ref={{cite book |url=https://web.archive.org/web/20110303222309/http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elementmagn.pdf|chapter=Magnetic susceptibility of the elements and inorganic compounds| editor = Lide, D. R. | title = CRC Handbook of Chemistry and Physics | edition = 86th | location = Boca Raton (FL) | publisher = CRC Press | year = 2005 | isbn = 0-8493-0486-5 }}

|electrical resistivity unit prefix=µ

|electrical resistivity at 20=0.18

|thermal conductivity=46.1

|thermal expansion at 25=29.9

|speed of sound rod at 20=818

|magnetic susceptibility= {{val|−50.9|e=−6}}

|magnetic susceptibility ref= (298 K){{Cite book|title=CRC, Handbook of Chemistry and Physics|last=Weast|first=Robert|publisher=Chemical Rubber Company Publishing|year=1984|isbn=0-8493-0464-4|location=Boca Raton, Florida|pages=E110}}

|Young's modulus=8

|Shear modulus=2.8

|Bulk modulus=43

|Poisson ratio=0.45

|Mohs hardness=1.2

|Brinell hardness=26.5–44.7

|CAS number=7440-28-0

|naming=after Greek thallos, green shoot or twig

|discovered by=William Crookes

|discovery date=1861

|first isolation by=Claude-Auguste Lamy

|first isolation date=1862

|QID=Q932

}}