24 - Chromium transition metal
Discovered by Louis Nicolas Vauquelin in 1797
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 13 | 2 in 3s + 6 in 3p + 5 in 3d |
| 4 | 1 | 1 in 4s |
silvery metallic Appearance
52 u Atomic Mass
1.4 Å Atomic Radius
2.94k K Boiling Point
6 Group
3, 6 Common Oxidation States
1.39 Å Covalent Radius
7.19 g/cm³ Density
65.2 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s1 3d5 Electron Configuration
[Ar] 3d5 4s1 Electron Configuration (semantic)
1.66 Electronegativity
24 Electrons
6.77 eV First Ionization Energy
2, 3, 4, 5, 6 ICSD Oxidation States
652.9, 1590.6, 2987, 4743, 6702, 8744.9, 15455, 17820, 20190, 23580, 26130, 28750, 34230, 37066, 97510, 105800, 114300, 125300, 134700, 144300, 157700, 166090, 721870, 761733 kJ/mol Ionization Energies
2.13k K Melting Point
57 Mendeleev Number
23.4 J/(mol·K) Molar Heat
4 Number of Shells
28 Neutrons
24 Atomic Number
9 Number of Isotopes
-2, -1, 1, 2, 3, 4, 5, 6 Oxidation States
4 Period
Solid Phase
24 Protons
2, 8, 13, 1 Electron Shell Occupations