At high enough pressure, atomic material no longer exists, for example under the conditions of a neutron star. Is there a different maximal pressure above which covalent bonds no longer exist?

  • $\begingroup$ What do you mean by atomic material? Most other stars consist of plasma (which depends on temp and pressure), which could be considered to be an absence of chemical bonds since all particles are ionized. $\endgroup$
    – qwersjc
    Apr 25, 2014 at 3:56
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    $\begingroup$ This seems like it belongs in SE.Physics $\endgroup$
    – rch
    Apr 25, 2014 at 6:24
  • $\begingroup$ Vaguely related: Electron and neutron degeneracy. hyperphysics.phy-astr.gsu.edu/hbase/astro/whdwar.html#c3 and hyperphysics.phy-astr.gsu.edu/hbase/astro/pulsar.html#c1 are fun links $\endgroup$
    – rch
    Apr 25, 2014 at 10:18
  • $\begingroup$ @qwersjc, I think I'll have to make my question more specific. I would consider plasma atomic material until the last ionization is reached. I'll limit this question to covalent bonds, and maybe ask a different question for metallic or ionic bonding later. $\endgroup$
    – DavePhD
    Apr 25, 2014 at 10:51
  • $\begingroup$ I think you're looking for electron degenerate matter. As far as I understand, individual atomic nuclei still exist in EDM, but all the electrons are stripped, so it's sort of like a metal where all electrons are valence electrons. Maybe something like metallic hydrogen, a gas of electrons held together by a nuclear lattice. $\endgroup$ Apr 25, 2014 at 10:52

2 Answers 2


With the twist of thumbscrew, a hand-held diamond anvil cell will exert 300 GPa (43,500,000 psi). No chemical bonding problem there. If you stack stuff - planetary and stellar cores - it gets more interesting, depending on composition and temperature. Temperature matters.


Magnetic fields exert pressure. How much magnetic field diddles with chemical bonding to give you a pressure estimate?

10^10 teslas is 4.0×10^25 J/m^3 E/c^2 mass density more than 10^4 times that of lead.

That'll put some hurt on chemical bonding. Scale down to 347 kJ/mole-bond multiplied in a molar volume of diamond. Atomizing diamond requires about 800 kJ/mol per atom against cohesive energy. The strongest chemical bonding interaction is roughly 3 eV. Then you can pontificate with a Lennard-Jones potential.



Yes, covalently bonded substances become metals in sufficiently high pressures, which vary for different compounds. Unfortunately we still don't know much about really high pressures because they are difficult to generate - you can find details about metallic hydrogen and oxygen on Wikipedia.


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