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91 - Protactinium actinide

Discovered by William Crookes in 1917

Protactinium

Protactinium is a chemical element with symbol Pa and atomic number 91. It is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids. It forms various chemical compounds where protactinium is usually present in the oxidation state +5, but can also assume +4 and even +2 or +3 states.
Shell Electrons Orbitals
1 2 2 in 1s
2 8 2 in 2s + 6 in 2p
3 18 2 in 3s + 6 in 3p + 10 in 3d
4 32 2 in 4s + 6 in 4p + 10 in 4d + 14 in 4f
5 20 2 in 5s + 6 in 5p + 10 in 5d + 2 in 5f
6 9 2 in 6s + 6 in 6p + 1 in 6d
7 2 2 in 7s
ProtactiniumPa Electron 1 Electron 2 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 10 Electron 11 Electron 12 Electron 13 Electron 14 Electron 15 Electron 16 Electron 17 Electron 18 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 10 Electron 11 Electron 12 Electron 13 Electron 14 Electron 15 Electron 16 Electron 17 Electron 18 Electron 19 Electron 20 Electron 21 Electron 22 Electron 23 Electron 24 Electron 25 Electron 26 Electron 27 Electron 28 Electron 29 Electron 30 Electron 31 Electron 32 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 10 Electron 11 Electron 12 Electron 13 Electron 14 Electron 15 Electron 16 Electron 17 Electron 18 Electron 19 Electron 20 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 1 Electron 2
231.04  u Atomic Mass
4300  K Boiling Point
2  Å Covalent Radius
15.37  g/cm³ Density
53.03 Electron Affinity
1.5 Electronegativity
5.89  eV First Ionization Energy
1873.15  K Melting Point
7 Number of Shells
91 Atomic Number