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24
Cr
51.996
Chromium |
Appearance & Characteristics | Reactions |
Other Forms Radius | Conductivity | Abundance
General:
| Name: Chromium | Symbol: Cr |
| Group: Trans. Met. | Atomic weight: 51.996 |
| Density @ 293 K: 7.19 g/cm3 | Atomic volume: 7.23 cm3/mol |
| Group: Trans. Met. | Discovered: 1798 |
States
| State (s, l, g): solid | |
| Melting point: 2180 K (1907 oC) | Boiling point: 2945 K (2672 oC) |
| Heat of fusion: 16.90 kJ/mol | Heat of vaporization: 344.30 kJ/mol |
Energies
| 1st ionization energy: 652.8 kJ/mole | |
| Electronegativity: 1.66 | 2nd ionization energy: 1592 kJ/mole |
| Electron affinity: 64.3 kJ/mole | 3rd ionization energy: 2987.2 kJ/mole |
| Specific heat: 0.45 J/gK | Heat atomization: 397 kJ/mole atoms |
Oxidation & Electrons
| Shells: 2,8,13,1 | Electron configuration: [Ar] 3d5 4s1 |
| Minimum oxidation number: -2 | Maximum oxidation number: 6 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 6 |
Appearance & Characteristics
| Structure: bcc: body-centered cubic | Color: silvery-white |
| Uses: CrO2 tape, paint, steel | Toxicity: |
| Hardness: 9 mohs | Characteristics: hard |
Reactions
| Reaction with air: none | |
| Reaction with 6 M HCl: mild, => H2, CrCl3 | Reaction with 6 M HCl: mild, => H2, CrCl3 |
| Reaction with 15 M HNO3: passivated | Reaction with 6 M NaOH: |
Other Forms
| Number of isotopes: 4 | Hydride(s): CrH |
| Oxide(s): Cr2O3 CrO2 CrO3 + non-stoich | Chloride(s): CrCl2 CrCl3 |
Radius
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
| Atomic radius: 128 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): 90.5 pm | Ionic radius (3+ ion): 75.5 pm |
Conductivity
| Thermal conductivity: 93.9 J/m-sec-deg | |
| Electrical conductivity: 77.519 1/mohm-cm | Polarizability: 11.6 A^3 |
Abundance
| Source: Chromite (oxide) | |
| Rel. abund. solar system: 4.130 log | Abundance earth's crust: 2 log |
| cost, pure: 10 $/100g | cost, bulk: $/100g |
