H

Hafnium

IUPAC: Hafnium

Hf Elements CAS 7440-58-6
Quick Reference
Formula / NotationHf
CAS Number7440-58-6
Molecular Weight178.49
Melting Point2233.0
Boiling Point4603.0
Density13.31
SolubilityInsoluble in water
AppearanceLustrous, silvery-grey metal
Also Known AsHf, hafnium metal
CategoryElements

What is Hafnium?

Hafnium is a lustrous, silvery transition metal, atomic number 72. Always found with zirconium (very similar chemistry). High neutron absorption cross-section makes it ideal for nuclear reactor control rods. Also critical in semiconductor gate dielectrics.

Formula & Notation

Hf

IUPAC Name: Hafnium

Other Names / Synonyms: Hf, hafnium metal

Properties & Characteristics

Atomic number: 72. Atomic mass: 178.49 g/mol. Period 6, Group 4. Melting point: 2233 C. Boiling point: 4603 C. Density: 13.31 g/cm3. Electronegativity: 1.30. Oxidation state: +4. Six stable isotopes. Very similar to Zr (lanthanide contraction). High neutron absorption.

Physical Data

PropertyValue
Melting Point2233.0
Boiling Point4603.0
Density13.31
Molecular Weight178.49
SolubilityInsoluble in water
AppearanceLustrous, silvery-grey metal

Uses & Applications

Nuclear reactor control rods (high neutron absorption, corrosion resistant). Semiconductor gate dielectrics (HfO2 in advanced transistors - replaces SiO2 below 45 nm). High-temperature alloys. Plasma cutting torches. HfO2 refractory. X-ray tube cathodes.

Safety Information

Hafnium powder: pyrophoric and combustible - fire hazard. Hafnium metal: generally low toxicity. HfCl4: irritant, reacts with moisture. Handle powder under inert atmosphere. Separate from Zr in nuclear applications (Zr has low, Hf has high neutron absorption).

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Hafnium
Formula Hf
CAS Number 7440-58-6
Molecular Weight 178.49
Category Elements
Synonyms Hf, hafnium metal

Frequently Asked Questions

Hafnium is a lustrous, silvery transition metal, atomic number 72. Always found with zirconium (very similar chemistry). High neutron absorption cross-section makes it ideal for nuclear reactor control rods. Also critical in semiconductor gate dielectrics.

More "H" Terms

View all "H" terms →
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z