91  Protactinium

 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      

+--------------------+
| 91  ____           |
|    |  _ \ __ _     |
|    | |_) / _` |    |
|    |  __/ (_| |    |
|    |_|   \__,_|    |
|                    |
|    Protactinium    |
|     231.03588 u    |
+--------------------+

Electron Configuration: [Rn]7s2 5f2 6d1
Electronegativity:      1.5
Atomic Radius:          243 pm
Ionization Energy:      5.89 eV
Electron Affinity:      
Oxidation States:       +5, +4
Standard State:         Solid
Melting Point:          1845 K
Boiling Point:          
Density:                15.37 g/cm3
Family:                 Actinide
Year Discovered:        1913
Number of Neutrons:     140
Number of Protons:      91
Number of Electrons:    91
Number of Valence:      
Valency:                
Group:                  
Period:                 7
Shell:                  f-shell
Specific Heat:          
Radioactive:            1
Occurrence:             Natural
Source:                 Radioactive decay