Room of the Elements · No. 96

Curium (Cm): what kind of element is it?

In short

Curium is element number 96, with the symbol Cm. Its name comes from the Curies, who discovered polonium and radium.

Atomic number 96(247)

CmCuriumキュリウム (kyuriumu)

Symbol: Cm
Atomic weight: (247)
Place in the table: Period 7 · Actinoids

The number in parentheses is not an atomic weight. It is the mass number of one radioactive isotope of the element.

Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.

The Curies

Curium was discovered in 1944 and named after the Curies, who isolated radium and discovered polonium. It is one of the elements named after people.

Where it sits on the table

The fifteen elements from actinium to lawrencium are called the actinoids. On the Room of the Elements table they are in the lower of the two rows set apart at the bottom.

Directly above it on the table is gadolinium, named after the researcher Gadolin. Names of people line up vertically.

Think about it

Q1What do you think of leaving researchers’ names on elements?
Q2Can you name the two elements the Curies discovered?
Q3Look for elements named after people in the Room of the Elements.

There is no single right answer. Talking it over with someone at home is a good way to learn.

Did you know? — Elements named after people are common toward the bottom of the table, among the artificial elements.

Next steps

About this page
Symbol and atomic weight: Chemical Society of Japan, “Table of Standard Atomic Weights (2026)” and “Table of Atomic Weights with Four Significant Figures (2026)”. Origin of the symbol and year of discovery: Sugiyama, “The Origins of Element Symbols,” Kagaku to Kyōiku 43(12), 1995 (Chemical Society of Japan). All sources are in Japanese.
Written by CCN CO., LTD.

Previous Next