72
Room of the Elements · No. 72
Hafnium (Hf): what kind of element is it?
日本語
In short
Hafnium is element number 72, a metal with the symbol Hf. Its name comes from Hafnia, the Latin name for Copenhagen, the capital of Denmark.
Atomic number 72178.5
HfHafniumハフニウム (hafuniumu)- Symbol
- Hf
- Atomic weight
- 178.5
- Place in the table
- Period 6 · Group 4
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
A city’s name
Hafnium was discovered in 1923 and named after Copenhagen. It is a fairly new element, found in the 20th century.
Where it sits on the table
Hafnium is in the sixth row of Group 4, with zirconium above and titanium above that. In the sixth row, it comes right after the lanthanoids (57–71).
Think about it
- Q1Look for other elements named after cities.
- Q2Why do you think hafnium wasn’t found until 1923?
- Q3Zirconium and hafnium are one above the other. Do you think they are alike?
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — Some elements found in the 20th century are named after places, like hafnium (Copenhagen, 1923) and rhenium (the Rhine, 1925).