Elements with intermediate properties
Metalloids are elements that have properties of both metals and nonmetals. They include boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. They are the foundation of modern electronics as semiconductors.
Read in glossarySilicon is the basis of all modern electronics, from computers to smartphones
Arsenic was historically used as poison due to its lack of taste and smell
Germanium was predicted by Mendeleev as 'eka-silicon' 15 years before its discovery
Boron is extremely hard and is used in rocket engines
Polonium is one of the most radioactive elements, used as a poison
Metalloids have 3-6 valence electrons and are located at the boundary between metals and nonmetals in the periodic table. Their electronic structure allows for adjustable conductivity.
Metalloids have low to moderate reactivity. Silicon and germanium are fairly inert, while arsenic and antimony react with halogens and acids.
| Element | Z | Mass u | M.P. °C | B.P. °C | ρ г/см³ | EN |
|---|---|---|---|---|---|---|
B Boron | 5 | 10.81 ▼ | 2076 ▲ | 4000 ▲ | 2.34 | 2.04 |
Si Silicon | 14 | 28.09 | 1414 | 3265 | 2.33 ▼ | 1.90 ▼ |
Ge Germanium | 32 | 72.63 | 938 | 2833 | 5.32 | 2.01 |
As Arsenic | 33 | 74.92 | 817 | 614 ▼ | 5.73 | 2.18 ▲ |
Sb Antimony | 51 | 121.76 | 631 | 1587 | 6.70 | 2.05 |
Te Tellurium | 52 | 127.60 | 450 | 988 | 6.24 | 2.10 |
Po Polonium | 84 | 209.00 ▲ | 254 ▼ | 962 | 9.32 ▲ | 2.00 |
The term 'metalloid' comes from Greek 'metallon' (metal) + 'eidos' (similar). The name reflects the intermediate properties of these elements between metals and nonmetals.
Berzelius first obtained pure silicon, although its existence was known earlier
Clemens Winkler discovered germanium, confirming Mendeleev's prediction
Invention of the germanium transistor at Bell Labs — the beginning of the electronic era
Texas Instruments created the first silicon transistor, changing the industry
Discovered germanium, confirming Mendeleev's periodic law
Isolated pure silicon, boron, and other elements
Co-inventor of the transistor, Nobel Prize 1956