107
  Bh  
264.000000
Bohrium

Name: Bohrium
Symbol: Bh
Atomic Number: 107
Atomic Weight: 264.000000
Family: Transition Metal
CAS RN: 54037-14-8
Description: A synthetic element not present in nature, appearance unknown, probably metallic solid.
State (25C): Unknown (Synthetic)
Oxidation states: unknown

Molar Volume: unknown
Valence Electrons: 6d57s2

Boiling Point:  unknown
Melting Point:
unknown
Electrons Energy Level: 2, 8, 18, 32, 32, 13, 2
Isotopes: 16 + None Stable
Heat of Vaporization: unknown
Heat of Fusion: unknown
Density: unknown
Specific Heat: unknown
Atomic Radius: unknown
Ionic Radius: unknown
Electronegativity: unknown
Vapor Pressure: unknown
1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d5 7s2

History

Bohrium was synthesized in 1976 by a Soviet team led by Y. Oganessian at the Joint Institute for Nuclear Research at Dubna, Russia, who produced isotope 261Bh with a half-life of 1-2 ms (later data gave a half life of around 10 ms).  They did this by bombarding bismuth-204 with heavy nuclei of chromium-54.

In 1981 a German research team led by Peter Armbruster and Gottfried Munzenberg at the Gesellschaft fur Schwerionenforschung (Institute for Heavy Ion Research) in Darmstadt were also able to confirm the Soviet team's results and produce bohrium, this time the longer-lived Bh-262.

The Germans suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr.  The Soviets had suggested this name be given to element 105 (dubnium).

Bohr.jpg (17981 bytes)

Niels Bohr

There was an element naming controversy as to what the elements from 101 to 109 were to be called; thus IUPAC adopted unnilseptium, symbol Uns) as a temporary, systematic element name for this element.  In 1994 a committee of IUPAC recommended that element 107 be named bohrium.  While this conforms to the names of other elements honoring individuals, where only the surname is taken, it was opposed by many who were concerned that it could be confused with boron.  Despite this, the name bohrium for element 107 was recognized internationally in 1997.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10 5f14
6s2 6p6 6d5
7s2

Isotopes

Bohrium is a synthetic element whose most stable isotope, Bh-267, has a half-life of 22 seconds.

atom.gif (700 bytes)

Isotope  Atomic Mass  Half-Life
260Bh 260.12197 ~0.3 ms
261Bh 261.12166 13 ms
262Bh 262.12289 290 ms
263Bh 263.12304 ~200 ms
264Bh 264.1246 1.3 seconds
265Bh 265.12515 0.9 seconds
266Bh 266.12694 5 seconds
267Bh 267.12765 22 seconds
268Bh 268.12976 ~25 seconds
269Bh 269.13069 ~25 seconds
270Bh 270.13362 ~30 seconds
271Bh 271.13518 ~40 seconds
272Bh 272.13803 10 seconds
273Bh 273.13962 ~90 minutes
274Bh 274.14244 ~90 minutes
275Bh 275.14425 ~40 minutes

atom.gif (700 bytes)

Bohrium Data
 

Atomic Structure

  • Atomic Radius:
  • Atomic Volume:
  • Covalent Radius:
  • Cross Section (Thermal Neutron Capture) Barns: 
  • Crystal Structure:
  • Electron Configuration:
    1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d5 7s2
  • Electrons per Energy Level: 2, 8, 18, 32, 32, 13, 2
  • Ionic Radius:
  • Filling Orbital:
  • Number of Electrons (with no charge): 107
  • Number of Neutrons (most common/stable nuclide): 155
  • Number of Protons: 107
  • Oxidation States:
  • Valence Electrons:

Chemical Properties

  • Electrochemical Equivalent:
  • Electron Work Function:
  • Electronegativity: N/A (Pauling); N/A (Allrod Rochow)
  • Heat of Fusion: kJ/mol
  • Incompatibilities:
  • Ionization Potential
    • First:
  • Valence Electron Potential (-eV):

Physical Properties

  • Atomic Mass Average: 262
  • Boiling Point:
  • Coefficient of Lineal Thermal Expansion/K-1: N/A
  • Conductivity
    Electrical:
    Thermal:
  • Description:
    Man made radioactive element
  • Flammablity Class:
  • Freezing Point: see melting point
  • Heat of Vaporization: kJ/mol
  • Melting Point:
  • Physical State (at 20C & 1atm):
  • Specific Heat:
  • Vapor Pressure:

Regulatory / Health

  • CAS Number
    • 54037-14-8
  • NFPA 704
    • Health:
    • Fire:
    • Reactivity:
    • Special Hazard: Radioactive<
    • OSHA Permissible Exposure Limit (PEL)
      • No limits set by OSHA
    • OSHA PEL Vacated 1989
      • No limits set by OSHA
    • NIOSH Recommended Exposure Limit (REL)
      • No limits set by NIOSH
    • Levels In Humans:
      Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
      • Blood/mg dm-3: nil
      • Bone/p.p.m: nil
      • Liver/p.p.m: nil
      • Muscle/p.p.m: nil
      • Daily Dietary Intake: nil
      • Total Mass In Avg. 70kg human: nil

    Who / Where / When / How

    • Discoverer: Soviet scientists at the Joint Institute for Nuclear Research
    • Discovery Location: Dubna, USSR
    • Discovery Year: 1975
    • Name Origin:
      Named in honor of the Danish physicist Niels Bohr
    • Abundance:
      • Earth's Crust/p.p.m.: nil
      • Seawater/p.p.m.: nil
      • Atmosphere/p.p.m.: nil
      • Sun (Relative to H=1E12): N/A
    • Sources:
      Synthetically by bombarding Bi204 with heavy nuclei of CR54.
    • Uses:
      None
    • Additional Notes:
      In 1975 Soviet scientists in Dubna were able to synthesize element 107 which then existed for only 2/1000's of a second. Physicists at the Heavy Ion Research Laboratory in Darmstadt West Germany confirmed this discovery in 1981 by synthesizing and identifying six nuclei of the element. In August of 1997 the International Union of Pure and Applied Chemistry announced the official naming of this element as Bohrium. Like many elements, the discovery date for this element varies from reference source to reference source. We speculate that this is caused by academic and geo-political rivalries.

Transition Metals
Group 3
(IIIB)
4
(IVB)
5
(VB)
6
(VIB)
7
(VIIB)
8
(VIIIB)
9
(VIIIB)
10 (VIIIB) 11
(IB)
12
(IIB)
Period 4 21
Sc
44.95
22
Ti
47.86
23
V
50.94
24
Cr
51.99
25
Mn
54.93
26
Fe
55.84
27
Co
58.93
28
Ni
58.69
29
Cu
63.54
30
Zn
65.39
Period 5 39
Y
88.90
40
Zr
91.22
41
Nb
92.90
42
Mo
95.94
43
Tc
98.00
44
Ru
101.0
45
Rh
102.9
46
Pd
106.4
47
Ag
107.8
48
Cd
112.4
Period 6 57
La
138.9
72
Hf
178.4
73
Ta
180.9
74
W
183.8
75
Re
186.2
76
Os
190.2
77
Ir
192.2
78
Pt
195.0
79
Au
196.9
80
Hg
200.5
Period 7 89
Ac
227.0
104
Rf
261.0
105
Db
262.0
106
Sg
266.0
107
Bh
264.0
108
Hs
269.0
109
Mt
268.0
110
Ds
269.0
111
Rg
272.0
112
Uub
277.0