 |
| General |
| Name | Chromium |
| Symbol | Cr |
| Number | 24 |
| Group Number | 6 |
| Group | Transition metals |
| Block | d |
| Density | 7.19 g/cm3 |
| Atomic Weight | 51.996 g/mol |
| Atomic Volume | 7.23 cm3/mol |
| Discover | 1798 |
|
| States |
| State | Solid |
| Melting Point | 2180 K |
| Boiling Point | 2944 K |
| Triple Point | Nil |
| Critical Point | Nil |
| Heat of Fusion | 21.0 kJ/mol |
| Heat of Vaporization | 339.5 kJ/mol |
|
| Energies |
| First Ionization Energy | 652.8 kJ/mole |
| Second Ionization Energy | 1592 kJ/mole |
| Third Ionization Energy | 2987.2 kJ/mole |
| Electronegativity | 1.66 |
| Electron Affinity | 64.3 kJ/mole |
| Specific Heat | 0.45 J/gK |
| Heat Atomization | 397 kJ/mole atoms |
|
| Oxidation and Electrons |
| Shells | 2,8,13,1 |
| Electron Configuration | [Ar] 3d5 4s1 |
| Minimum Oxidation Number | -2 |
| Maximum Oxidation Number | 6 |
| Minimum Common Oxidation Number | 0 |
| Maximum Common Oxidation Number | 6 |
|
| Appearance and Characteristics |
| Crystal Structure | cubic body centered |
| Characteristics | hard |
| Color | silvery-white |
| Uses | CrO2 tape, paint, steel |
| Hardness | 9 mohs |
| Toxicity | No |
|
| Reactions |
| Reaction with Air | None |
| Reaction with 6M HCl | mild, =>H2, CrCl3 |
| Reaction with 15M HNO3 | passivated |
| Reaction with 6M NaOH | None |
|
| Other Forms |
| Number of Isotopes | 4 |
| Hydride | CrH |
| Oxide | Cr2O3 CrO2 CrO3+non-stoich |
| Chloride | CrCl2 CrCl3 |
|
| Radius |
| Atomic Radius | 128 pm |
| Ionic Radius (1+ ion) | Nil |
| Ionic Radius (1- ion) | Nil |
| Ionic Radius (2+ ion) | 90.5 pm |
| Ionic Radius (2- ion) | Nil |
| 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 A3 |
|
| Abundance |
| Source | Chromite (oxide) |
| Relation Abundance Solar System | 4.130 log |
| Abundance Earth's Crust | 2 log |
|
