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21
Room of the Elements · No. 21

Scandium (Sc): what kind of element is it?

日本語

In short

Scandium is element number 21, a metal with the symbol Sc. It is one of the elements that Mendeleev, who created the periodic table, predicted before it was discovered.
Atomic number 2144.96
ScScandium (sukanjiumu)
Symbol
Sc
Atomic weight
44.96
Place in the table
Period 4 · Group 3

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

An element from Scandinavia

In 1879, the Swedish analytical chemist Nilson found a new element in ores from Sweden and named it scandium. The symbol Sc comes from the Latin for Scandinavia.

The predicted “eka-boron”

The Russian chemist Mendeleev published his periodic table in 1869 and left gaps for elements not yet discovered. One of them he called “eka-boron.”

Nilson did not know about the prediction, but at almost the same time a chemist named Cleve showed that scandium was exactly the eka-boron Mendeleev had predicted.

Think about it

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

Did you know? — Mendeleev’s predicted “eka-boron,” “eka-aluminium” and “eka-silicon” were all found within 20 years: scandium, gallium and germanium.
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). Mendeleev’s table and predictions, Nilson’s discovery and Cleve’s finding: “International Year of the Periodic Table 2019 (150 years of the periodic table),” Kagaku to Kyōiku 67(6), 2019. All sources are in Japanese.
Written by CCN CO., LTD.
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