Germanium

The element germanium, symbol Ge and atomic number 32, is part of a frequently studied group of elements, Group IVa of the periodic table, which could have applications for next-generation computer architecture. It is currently used in fiber-optic systems, specialized camera and microscope lenses, circuitry, and solar cells. It is a semi-conductor so it is useful in electronics.

In 1869, Dmitri Mendeleev predicted the existence of an element in Germanium's position in his periodic table and called the element eka-silicon. Mendeleev predicted the properties of this undiscovered element based on the properties of the elements around it. In 1886 Clemens Winkler found the element in the mineral argyrodite, named it after his homeland, Germany, and reported its properties. Winkler's observed properties for germanium agreed very well with Mendeleev's predictions for ekasilicon:

Property	Ekasilicon	Germanium
atomic mass	72.64	72.59
density (g/cm3)	5.5	5.35
melting point (°C)	high	947
color	gray	gray
oxide type	dioxide	dioxide
oxide density (g/cm3)	4.7	4.7
oxide activity	weak base	weak base

Germanium can form compounds similar to those formed by carbon and silicon.
Germane, GeH₄, is a compound similar in structure to methane, CH₄.
Polygermanes with general formula Ge_nH_2n+2, where n is 1 to 5, are known.

Germanium is a semiconducting solid at room temperature and pressure. It has been predicted that, under pressure, the element should exhibit superconductivity, meaning that there is no resistance to the flow of an electric current.

Scientists at the Geophysical Laboratory at Carnegie Institution for Science have recently discovered that under pressure of 66 GPa (about 650,000 atmospheres), germanium undergoes a structural change from one type of solid material to another that is metallic, meaning it conducts electricity.

Reference
Xiao-Jia Chen, Chao Zhang, Yue Meng, Rui-Qin Zhang, Hai-Qing Lin, Viktor Struzhkin, Ho-kwang Mao. β-tin→Imma→sh Phase Transitions of Germanium. Physical Review Letters, 2011; 106 (13) DOI: 10.1103/PhysRevLett.106.135502

Further Reading
Periodic Table
History of the Periodic Table
Metals and Non-metals
Naming Carbon Compounds

Study Questions

1. Give the name and symbol for each element present in Group IVa of the Periodic Table.
   
2. Germanium is known to form germanium dioxide. Write the formula for germanium dioxide.
3. Which of the other Group IVa elements form dioxides? Give the name and formula for each of these compounds.
4. Could germanium form any other oxides? Explain your answer.
5. Draw up a table listing the electrical conductivity of each of the Group IVa elements. Explain any trend that you see.
6. Draw a structural formula for germane.
7. Explain why it would be predicted that germanium could form "polygermanes" similar to carbon's alkanes.
8. Predict the formula for the compound(s) formed between germanium and chlorine. Explain each prediction.