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 with the atomic number 43. 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. Bulk amounts of technetium are near impossible to obtain.

However, one can obtain it from certain element collector supplies as plated on metal foils. 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 radiation poisoning.

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