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Room of the Elements · No. 43

Technetium (Tc): what kind of element is it?

日本語

In short

Technetium is element number 43, with the symbol Tc. Its name means “artificial” in Greek. It was the first element ever made by people.
Atomic number 43(99)
TcTechnetium (tekunechiumu)
Symbol
Tc
Atomic weight
(99)
Place in the table
Period 5 · Group 7

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 first “element synthesis”

Mendeleev had called the element for gap number 43 “eka-manganese.”

In 1937, the Italian scientists Segrè and Perrier bombarded molybdenum with deuterons and made element 43, the first human “element synthesis.” Because it was made, it was named “artificial.”

The “nipponium” of number 43

In fact, in 1906, the Japanese chemist Ogawa Masataka had announced that he had found a new element number 43, which he called “nipponium.”

A little over a hundred years later, nihonium (element 113) became the first element with a name from Japan.

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? — Number 43 (the announced “nipponium”) and number 113 (nihonium): both numbers are linked to names from Japan.
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) (including Ogawa Masataka’s nipponium, 1906). Eka-manganese and the synthesis of technetium: “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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