Metalloids
Boron, silicon, germanium, arsenic, antimony and tellurium: elements on the staircase line with properties between metals and nonmetals.
What they have in common
Metalloids look metallic but are brittle, and they conduct electricity only moderately. That in-between conductivity is what makes silicon and germanium semiconductors, the basis of every microchip.
There is no single agreed list. The six above are included almost everywhere; polonium and astatine are sometimes added. Here polonium is shown as a post-transition metal and astatine as a halogen.
- Semiconductors
- Brittle solids with a metallic lustre
- Form amphoteric or weakly acidic oxides
Metalloids at a glance
| Element | Z | Mass | Configuration | Valence e⁻ | Charges | EN | Radius (pm) |
|---|---|---|---|---|---|---|---|
| Boron (B) | 5 | 10.811 | [He] 2s2 2p1 | 3 | 3+ | 2.04 | 82 |
| Silicon (Si) | 14 | 28.085 | [Ne] 3s2 3p2 | 4 | 4+ | 1.9 | 111 |
| Germanium (Ge) | 32 | 72.64 | [Ar] 3d10 4s2 4p2 | 4 | 4+ | 2.01 | 122 |
| Arsenic (As) | 33 | 74.922 | [Ar] 3d10 4s2 4p3 | 5 | 3− | 2.18 | 119 |
| Antimony (Sb) | 51 | 121.76 | [Kr] 4d10 5s2 5p3 | 5 | 3+, 5+ | 2.05 | 138 |
| Tellurium (Te) | 52 | 127.6 | [Kr] 4d10 5s2 5p4 | 6 | 2− | 2.1 | 135 |
Questions students ask
Where are metalloids on the periodic table?
Along the zig-zag “staircase” that runs from boron down to tellurium, separating metals (left) from nonmetals (right).