Technetium (Tc)

Technetium properties

Atomic number

43

Atomic mass

98 u

Category

Transition metal

Group

7

Period

5

Block

d-block

State at room temp.

Solid

Electronegativity

1.9

Melting point

2,430 K (2,156.8 °C)

Boiling point

4,538 K (4,264.8 °C)

Density

11 g/cm³

Valence electrons

2

Common charges

+4, +6, +7

Oxidation states

+7, +6, +4

Atomic radius

209 pm

Ionization energy

7.28 eV

Electron affinity

0.55 eV

Radioactive

Yes, no stable isotopes

Discovered

1937

Technetium electron configuration

The electron configuration of Technetium (Tc) is [Kr] 4d5 5s2. Its 43 electrons are arranged in shells as 2, 8, 18, 13, 2.

Protons, neutrons and electrons in Technetium

A neutral Technetium atom has 43 protons and 43 electrons. Most Technetium atoms have about 55 neutrons: the atomic mass rounded to 98, minus the atomic number 43.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Technetium have?

2

Technetium has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.

See every element: Periodic table with valence electrons

Technetium orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Technetium

98 g/mol

One mole of Technetium atoms (6.022 × 10²³ atoms) has a mass of 98 grams. Use this value to convert between grams and moles.

Technetium facts

• Technetium is the lightest element that has no stable isotopes; every form of it is radioactive.
• In 1952 astronomers detected technetium in red giant stars, showing that stars make heavy elements, because any technetium present when they formed would have decayed long ago.
• Technetium (Tc) has atomic number 43 and is a solid at room temperature. It was discovered in 1937.

Position in the periodic table

Technetium is element 43, in period 5 and group 7 of the periodic table, in the d-block.

All transition metals

Uses of Technetium

Technetium's main use is in medicine. The short-lived isotope technetium-99m is the most widely used radioactive tracer in diagnostic imaging, used in tens of millions of scans each year to examine bones, the heart, the thyroid, and other organs. Hospitals obtain it from generators containing molybdenum-99. Outside medicine it has few practical uses, though it has been studied as a corrosion inhibitor for steel.

Who discovered Technetium?

Italian scientists Emilio Segrè and Carlo Perrier identified technetium in 1937 at the University of Palermo, in a piece of molybdenum that had been bombarded with deuterons in Ernest Lawrence's cyclotron in Berkeley, California. It was the first element produced artificially, which is why its name comes from the Greek technetos, meaning 'artificial'.

Where does the name come from?

Technetium comes from the Greek technetos, meaning 'artificial'. Discovered in 1937 in metal that had been bombarded in a particle accelerator, it was the first element to be produced artificially.

Discovery timeline