Protactinium (Pa) is a chemical element of the periodic table, located in the period 7, and has the atomic number 91. It is the third element in the actinide series. It is a shiny, silvery-gray metal whose name comes from the Greek word “protos”, which means first. It is highly toxic and is counted as one of the radioactive elements.
| group | ⇨ | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| period | ⇩ | ||||||||||||||||||
| 1 | 1 H  Hydrogen |
2 He  Helium |
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| 2 | 3 Li  Lithium |
4 Be  Beryllium |
5 B  Boron |
6 C  Carbon |
7 N  Nitrogen |
8 O  Oxygen |
9 F  Fluorine |
10 Ne  Neon |
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| 3 | 11 Na  Sodium |
12 Mg  Magnesium |
13 Al  Aluminium |
14 Si  Silicon |
15 P  Phosphorus |
16 S  Sulfur |
17 Cl  Chlorine |
18 Ar  Argon |
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| 4 | 19 K  Potassium |
20 Ca  Calcium |
21 Sc  Scandium |
22 Ti  Titanium |
23 V  Vanadium |
24 Cr  Chromium |
25 Mn  Manganese |
26 Fe  Iron |
27 Co  Cobalt |
28 Ni  Nickel |
29 Cu  Copper |
30 Zn  Zinc |
31 Ga  Gallium |
32 Ge  Germanium |
33 As  Arsenic |
34 Se  Selenium |
35 Br  Bromine |
36 Kr  Krypton |
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| 5 | 37 Rb  Rubidium |
38 Sr  Strontium |
39 Y  Yttrium |
40 Zr  Zirconium |
41 Nb  Niobium |
42 Mo  Molybdenum |
43 Tc  Technetium |
44 Ru  Ruthenium |
45 Rh  Rhodium |
46 Pd  Palladium |
47 Ag  Silver |
48 Cd  Cadmium |
49 In  Indium |
50 Sn  Tin |
51 Sb  Antimony |
52 Te  Tellurium |
53 I  Iodine |
54 Xe  Xenon |
|
| 6 | 55 Cs  Caesium |
56 Ba  Barium |
72 Hf  Hafnium |
73 Ta  Tantalum |
74 W  Tungsten |
75 Re  Rhenium |
76 Os  Osmium |
77 Ir  Iridium |
78 Pt  Platinum |
79 Au  Gold |
80 Hg  Mercury |
81 Tl  Thallium |
82 Pb  Lead |
83 Bi  Bismuth |
84 Po  Polonium |
85 At  Astatine |
86 Rn  Radon |
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| 7 | 87 Fr  Francium |
88 Ra  Radium |
104 Rf  Rutherfordium |
105 Db  Dubnium |
106 Sg  Seaborgium |
107 Bh  Bohrium |
108 Hs  Hassium |
109 Mt  Meitnerium |
110 Ds  Darmstadtium |
111 Rg  Roentgenium |
112 Cn  Copernicium |
113 Nh  Nihonium |
114 Fl  Flerovium |
115 Mc  Moscovium |
116 Lv  Livermorium |
117 Ts  Tennessine |
118 Og  Oganesson |
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| 57 La  Lanthanum |
58 Ce  Cerium |
59 Pr  Praseodymium |
60 Nd  Neodymium |
61 Pm  Promethium |
62 Sm  Samarium |
63 Eu  Europium |
64 Gd  Gadolinium |
65 Tb  Terbium |
66 Dy  Dysprosium |
67 Ho  Holmium |
68 Er  Erbium |
69 Tm  Thulium |
70 Yb  Ytterbium |
71 Lu  Lutetium |
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| 89 Ac  Actinium |
90 Th  Thorium |
91 Pa Protactinium |
92 U  Uranium |
93 Np  Neptunium |
94 Pu  Plutonium |
95 Am  Americium |
96 Cm  Curium |
97 Bk  Berkelium |
98 Cf  Californium |
99 Es  Einsteinium |
100 Fm  Fermium |
101 Md  Mendelevium |
102 No  Nobelium |
103 Lr  Lawrencium |
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| – f block |
Protactinium Element Information
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| Origin of name | Greek word “protos” (which means first) |
| Symbol | Pa |
| Atomic number (Z) | 91 |
| Atomic mass | 231.03588 u |
| Block | f-block |
| Period | 7 |
| Classification | Actinide |
| Atomic radius | 163 pm |
| Covalent radius | 200 pm |
| Melting point | 1568 ℃, 2854 ℉, 1841 K |
| Boiling point | 4027 ℃, 7280 ℉, 4300 K |
| Electron configuration | [Rn] 5f2 6d1 7s2 |
| Electrons per shell | 2, 8, 18, 32, 20, 9, 2 |
| Crystal structure | Body-centered tetragonal |
| Phase at r.t | Solid |
| Density near r.t | 15.37 g/cm3 |
| Natural occurrence | From decay |
| Oxidation state | +5 |
| Electronegativity (Pauling scale) | 1.5 |
| Protons Neutrons Electrons |
91 140 91 |
| CAS number | 7440-13-3 |
| Discovered by | Kasimir Fajans and Oswald Helmuth Göhring in 1913 |
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Related:
More Elements:
External Links:
- https://www.rsc.org/periodic-table/element/91/protactinium
- https://en.wikipedia.org/wiki/Protactinium
- https://www.britannica.com/science/protactinium
- https://pubchem.ncbi.nlm.nih.gov/element/Protactinium
- https://www.chemicool.com/elements/protactinium.html
- https://www.livescience.com/39728-protactinium.html
