Jun 18 2012
Chemical Formula
Ge
Topics Covered
BackgroundBasic
InformationOccurrence
Production of GermaniumIsotopes
Health AspectsKey PropertiesApplications
Background
Russian Chemist Dmitri Mendeleev, who developed the periodic table, predicted
that a new element will be discovered to fill an empty spot in the table. In
1886AD, Germanium was discovered by German chemist, Clemens Alexander Winkler.
In 1885, a new ore was found in a mine near Freiberg, Germany. The ore
contained silver and sulfur. Winkler isolated a new element from the ore and
named it as germanium. The name germanium is derived from Germany, which is the
native country of Winkler.
Germanium is a metalloid like silicon and as such is used to make
semiconductor devices.
Basic Information
Table 1. Basic Properties of Germanium
| Name |
Germanium |
| Symbol |
Ge |
| Atomic number |
32 |
| Atomic weight |
72.64 amu |
| Standard state |
solid at 298 K |
| CAS Registry ID |
7440-56-4 |
| Group in periodic table |
14 |
| Group name |
None |
| Period in periodic table |
4 |
| Block in periodic table |
p-block |
| Colour |
Grayish white |
| Classification |
Semi-metallic |
| Melting Point |
1211.40 K (938.25°C or 1720.85°F) |
| Boiling Point |
3106 K (2833°C or 5131°F) |
| Density |
5.323 g/cm3 |
| Number of Stable Isotopes |
4 |
| Ionization Energy |
7.900 eV |
| Oxidation States |
+4, +2 |
|
|
Occurrence
Germanium is found in the Earth's crust. Argyrodite and germanite are the
main germanium-containing minerals, with only African deposits of Germanite
being regarded as significant.
Production of Germanium
Germanium is most commonly refined from by-products of non-ferrous (in particular zinc) production and from coal ash. Germanium concentrates are oxidised by heating in air and converted to GeCl4 using concentrated chlorohydric acid, which is then hydrolysed to form GeO2, which is in turn reduced in hydrogen at temperatures of 600-700°C to yield germanium.
Isotopes
Germanium comprises five naturally occurring isotopes that include
germanium-70, germanium-72, germanium-73, germanium-74 and germanium-76. Their
only application is in the manufacture of medical radioisotopes as follows:
- Ge-74 to produce As-74
- Ge-76 to produce As-77
- Ge-74 to produce As-73
- Ge-72 to produce As-72
Health Aspects
Germanium chloride (GeCl4) and germanium fluoride (GeF4
) can cause irritation to the eyes, skin, lungs and throat.
Key Properties
The key properties of Germanium are:
- It is a Gray-white brittle metal, is bright, shiny and silvery in color
- Is brittle and breaks apart easily unlike other metals
- It is a relatively inactive element
- It is a poor conductor of electricity, can be classified as a semiconductor
- It is insoluble with water and does not react with oxygen at room
temperature
- It dissolves in hot acids and with oxygen at high temperature
- When finely divided, it becomes more active
Applications
The applications of Germanium are listed below:
- Germanium's main use is to produce solid-state electronics, semiconductors
and fiber optic systems.
- As a phosphor in fluorescent lamps
- It is used in infra red optics, in particular for thermal imaging in
milatrya nd firefighting applications
- Germanium is used to manufacture rectifiers, transistors and
weapons-sighting systems and used as a fluorescent material.
- Alloying agent
- Germanium can also be used as a catalyst to produce plastics.
Source: AZoM.com