81  Thallium

 H                                                  He
 Li Be                               B  C  N  O  F  Ne
 Na Mg                               Al Si P  S  Cl Ar
 K  Ca Sc Ti V  Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
 Rb Sr Y  Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I  Xe
 Cs Ba La Hf Ta W  Re Os Ir Pt Au Hg[Tl]Pb Bi Po At Rn
 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
                                                      
       Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu      
       Th Pa U  Np Pu Am Cm Bk Cf Es Fm Md No Lr      

+--------------------+
| 81    _____ _      |
|      |_   _| |     |
|        | | | |     |
|        | | | |     |
|        |_| |_|     |
|                    |
|      Thallium      |
|      204.383 u     |
+--------------------+

Electron Configuration: [Xe]6s2 4f14 5d10 6p1
Electronegativity:      1.62
Atomic Radius:          196 pm
Ionization Energy:      6.108 eV
Electron Affinity:      0.2 eV
Oxidation States:       +3, +1
Standard State:         Solid
Melting Point:          577 K
Boiling Point:          1746 K
Density:                11.8 g/cm3
Family:                 Post-transition metal
Year Discovered:        1861
Number of Neutrons:     123
Number of Protons:      81
Number of Electrons:    81
Number of Valence:      3
Valency:                3
Group:                  13
Period:                 6
Shell:                  p-shell
Specific Heat:          0.129 J/g K
Radioactive:            0
Occurrence:             Natural
Source:                 Dying low-mass stars