Germanium vs Silicon
Both are metalloids, so they share the same broad chemistry.
The differences in plain English
- They sit in the same column, group 14, so they have the same number of outer electrons and react in similar ways; the heavier one, Germanium, is usually the more reactive of the two if they are metals, and the less reactive if they are non-metals.
- Both are solids at room temperature.
- Germanium is denser, about 2.3 times more than Silicon (5.323 against 2.329 g/cm³).
- Silicon melts at 1414 °C, far above Germanium at 938 °C.
- An atom of Germanium is about 2.6 times heavier than an atom of Silicon (72.63 u against 28.09 u).
- Germanium pulls electrons more strongly in a bond (electronegativity 2.01 against 1.9).
Side by side
| Germanium | Silicon | |
|---|---|---|
| Atomic number | 32 | 14 |
| Symbol | Ge | Si |
| Family | Metalloid | Metalloid |
| Group / period | 14 / 4 | 14 / 3 |
| State at room temperature | Solid | Solid |
| Atomic mass | 72.631 u | 28.085 u |
| Density | 5.323 g/cm³ | 2.329 g/cm³ |
| Melting point | 938 °C | 1414 °C |
| Boiling point | 2833 °C | 3265 °C |
| Electronegativity | 2.01 | 1.9 |
| First ionisation energy | 762 kJ/mol | 786.5 kJ/mol |
| Electron configuration | [Ar] 3d10 4s2 4p2 | [Ne] 3s2 3p2 |
| Discovered by | Clemens Winkler | Jöns Jacob Berzelius |
Germanium
The very first transistor, built at Bell Laboratories in December 1947, was a sliver of germanium with two gold contacts pressed against it. For a decade germanium was the material of the electronics revolution, until silicon proved cheaper and more forgiving of heat. Germanium never went away. Today it bends infrared light in thermal cameras, raises the refractive index inside optical fibres, and forms the base layer of the solar cells that power satellites.
- The first working transistor, demonstrated at Bell Labs in December 1947, used a small block of germanium.
- Germanium looks like a shiny metal but is transparent to infrared light, so thermal camera lenses are made from it.
Silicon
Silicon is the element that makes up most of the rock on Earth and most of the technology in your pocket. Combined with oxygen, it forms the silicate minerals of sand, granite, clay and the vast majority of the crust. Refined to a purity of one foreign atom in a billion, it becomes the crystal wafers on which transistors are printed, and the solar cells that turn sunlight into electricity.
- Silicon makes up about 28 per cent of the Earth's crust by mass, second only to oxygen.
- Like water, silicon expands as it freezes, so solid silicon floats on molten silicon.
Colour the bubbles by density or melting point and the difference jumps out.
More comparisons
Data from Periodic-Table-JSON (CC BY-SA); temperatures rounded to the nearest degree. Written by Anthony.