Element Chromium

Chromium ElementIt is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6.
It is a steely-grey, lustrous, hard and brittle transition metal.
Chromium is also the main additive in stainless steel, to which it adds anti-corrosive properties.
Chromium is also highly valued as a metal that is able to be highly polished while resisting tarnishing. Polished chromium reflects almost 70% of the visible spectrum, with almost 90% of infrared light being reflected.
The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, because many chromium compounds are intensely colored.
Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. Chromium is present in the environment in several different forms. The most common forms are chromium(0), chromium(III), and chromium(VI).
No taste or odor is associated with chromium compounds. Chromium(III) occurs naturally in the environment and is an essential nutrient.
Chromium(VI) and chromium(0) are generally produced by industrial processes.
The metal chromium, which is the chromium(0) form, is used for making steel. Chromium(VI) and chromium(III) are used for chrome plating, dyes and pigments, leather tanning, and wood preserving.

Names and Identifiers

Chemical Formula:Cr
CAS:7440-47-3
Molecular Weight:51.99610 g/mol
EC Number :231-157-5
MDL Number:MFCD00010944
Color:silvery metallic/ silver-gray
Other Names:Chrom, Cromo, Krom, Crômio
PubChem CID:23976
IUPAC Name:Chromium
Inchl:InChI=1S/Cr
InChI Key:VYZAMTAEIAYCRO-UHFFFAOYSA-N
Canonical SMILES:[Cr]
ICSC Number:0029

Physical & Chemical Properties

Phase:Solid
Density:7.19 g/cm³
Boiling Point:2944 K ​(2671 °C, ​4840 °F)
Melting Point:2180 K ​(1907 °C, ​3465 °F)
Molecular Formula:Cr
Flash Point:50 °F
Exact Mass:51.94050
Symbol:Globally Harmonized System of Classification
Signal Word:Warning
Hazard Statements:H410
Precautionary Statements:n/a
Hazard Codes:Xn:Harmful
Risk Phrases:R40
Safety Phrases:S16-S26-S36/37/39-S45-S36/37-S27
RIDADR:UN 2924 3/PG 2
WGK Germany:3
RTECS:GB4200000
Packaging Group:III
Hazard Class:4.1

Naturally occurring chromium is composed of three stable isotopes; 52Cr, 53Cr and 54Cr, with 52Cr being the most abundant (83.789% natural abundance). 19 radioisotopes have been characterized, with the most stable being 50Cr with a half-life of (more than) 1.8×1017 years, and 51Cr with a half-life of 27.7 days.

Naturally occurring isotopes

IsotopeMass/DaNatural abundance (atom %)Nuclear spin (I)Magnetic moment (μ/μN)
50Cr49.9460464 (17)4.345 (13)0
52Cr51.9405098 (17)83.789 (18)0
53Cr52.9406513 (17)9.501 (17)3/2-0.47454
54Cr53.9388825 (17)2.365 (7)0

Radiosotope data

IsotopeMass/DaHalf-lifeMode of decayNuclear spinNuclear magnetic moment
48Cr47.9540421.6 hEC to 48V
49Cr48.95134142.3 mEC to 49V5/20.476
51Cr50.94477227.70 dEC to 51V7/2-0.934
55Cr54.9408443.497 mβ to 55Mn3/2
56Cr55.940655.9 mβ to 56Mn0

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