Catenation

For carbon, the sigma overlap between adjacent atoms is sufficiently strong that perfectly stable chains can be formed.

Theories of the structure of water involve three-dimensional networks of tetrahedra and chains and rings, linked via hydrogen bonding.

[2] A polycatenated network, with rings formed from metal-templated hemispheres linked by hydrogen bonds, was reported in 2008.

[5] In unusual conditions, a 1-dimensional series of hydrogen molecules confined within a single wall carbon nanotube is expected to become metallic at a relatively low pressure of 163.5 GPa.

However, it is difficult to prepare and isolate SinH2n+2 (analogous to the saturated alkane hydrocarbons) with n greater than about 8, as their thermal stability decreases with increases in the number of silicon atoms.

[7][8] But with a suitable pair of organic substituents in place of hydrogen on each silicon it is possible to prepare polysilanes (sometimes, erroneously called polysilenes) that are analogues of alkanes.

[11] In dodecaborate(12) anion, twelve boron atoms covalently link to each other to form an icosahedral structure.

[citation needed] Nitrogen, unlike its neighbor carbon, is much less likely to form chains that are stable at room temperature.

In recent years, a variety of double and triple bonds between semi-metallic elements have been reported, including silicon, germanium, arsenic and bismuth.