Technetium

Technetium,  ₄₃Tc

General properties
Name, symbol	Technetium, Tc
Appearance	Silvery metallic
Technetium in the periodic table
Mn ↑ Tc ↓ Re Molybdenum ← Technetium → Ruthenium
Atomic number	43
Standard atomic weight (Ar)	98.907
Group, block	7; d-block
Period	period 5
Electron configuration	[Kr] 4d5 5s2
per shell	2, 8, 18, 13, 2
Physical properties
Phase	Solid
Density near r.t.	11 g/cm3
Heat of fusion	33.29 kJ/mol
Heat of	585.2 kJ/mol
Molar heat capacity	24.27 J/(mol·K)
pressure
Atomic properties
Oxidation states	−3, −1, 0, +1, +2, +3, +4, +5, +6, +7
Electronegativity	Pauling scale: 1.9 (Pauling scale)
energies	1st: 702 kJ/mol 2nd: 1470 kJ/mol 3rd: 2850 kJ/mol
Atomic radius	empirical: 136 pm
Covalent radius	147±7 pm
Miscellanea
Speed of sound thin rod	16,200 m/s (at 20 °C)
Thermal expansion	7.1 µm/(m·K) (at 20°C)
Thermal conductivity	50.6 W/(m·K)
Electrical resistivity	200 Ω·m (at 20 °C)
Magnetic ordering	Paramagnetic
CAS Registry Number	7440-26-8
History
Prediction	Dmitri Mendeleev ((1871))
Discovery and first isolation	Emilio Segrè and Carlo Perrier (1937)

Technetium is a radioactive, grey metal. It is the lightest element that has no stable isotopes.

Properties

Chemical

The chemical properties of technetium lie in between those of Manganese and Rhenium. It has 9 oxidation states, the most common oxidation states of technetium are +4, +5, and +7.

Physical

Technetium is a silvery radioactive metal.

Availability

Technetium is very rare and expensive. One can obtain it from certain element collector supplies. The price range is usually 400-1000€ for technetium plated foil.

Isolation

To do

Projects

- Element collection

Handling

Safety

Technetium has low chemical toxicity, but ingestion or inhalation is very dangerous since it leads to continuous internal irradiation.

Storage

The Tc⁹⁹ isotope can be stored in closed glass bottles, or, preferably, ampoules. All the other more active isotopes should be stored in containers with thick lead walls.

Disposal

To do