Element Hafnium

Hafnium ElementHafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Coster and Hevesy, making it the last stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered.

Names and Identifiers

Chemical Formula:Hf
CAS:7440-58-6
Molecular Weight:178.490 g/mol
EC Number :231-166-4
MDL Number:MFCD00011032
Color:silvery/ gray steel
Other Names:Afnio, Háfnio, Hafnio
PubChem CID:23986
IUPAC Name:Hafnium
Inchl:InChI=1S/Hf
InChI Key:VBJZVLUMGGDVMO-UHFFFAOYSA-N
Canonical SMILES:[Hf]
ICSC Number:0847

Physical & Chemical Properties

Phase:Solid
Density:13.31 g/cm³
Boiling Point:4876 K ​(4603 °C, ​8317 °F)
Melting Point:2506 K ​(2233 °C, ​4051 °F)
Molecular Formula:Hf
Flash Point:n/a
Exact Mass:179.946503
Symbol:Globally Harmonized System of Classification
Signal Word:Danger
Hazard Statements:H228
Precautionary Statements:P210
Hazard Codes:T+:Verytoxic;
Risk Phrases:R26/27/28;R35
Safety Phrases:S26-S27-S36/37/39-S45-S33-S16-S23
RIDADR:UN 3178 4.1/PG 3
WGK Germany:n/a
RTECS:n/a
Packaging Group:III
Hazard Class:8

At least 34 isotopes of hafnium have been observed, ranging in mass number from 153 to 186.
The five stable isotopes are in the range of 176 to 180. The radioactive isotopes’ half-lives range from only 400 ms for 153Hf, to 2.0 petayears (1015 years) for the most stable one, 174Hf

Naturally occurring isotopes

IsotopeMass/DaNatural abundance (atom %)Nuclear spin (I)Magnetic moment (μ/μN)
174Hf173.940044 (4)0.16 (1)0
176Hf175.941406 (4)5.26 (7)0
177Hf176.943217 (3)18.60 (9)7/20.7936
178Hf177.943696 (3)27.28 (7)0
179Hf178.9458122 (29)13.62 (2)9/2-0.6409
180Hf179.9465457 (30)35.08 (16)0

Radiosotope data

IsotopeMass/DaHalf-lifeMode of decayNuclear spinNuclear magnetic moment
172Hf171.939461.87 yEC to 172Lu0
173Hf172.940723.6 hEC to 173Lu1/2
175Hf174.94150470 dEC to 175Lu5/20.54
181Hf180.94909942.4 dβ to 181Ta1/2
182Hf181.950559 x 106 yβ to 182Ta0

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