[Iwonda (OP)]

The solar system started out as a cloud of gas and dust. I understand how rocky bodies form from the accretion process, but what causes gas and dust to become metal and ice? Is it possible that the formation of the sun has something to do with causing gas and dust to form ice and metal?

[chiralSPO]

The "dust" includes ices and metals.

[syhprum]

A small proportion of the dust is the result of supernovae explosions and an even smaller amount of heavy elements the result of Neutron star collisions.

[chiralSPO]

A small proportion of the dust is the result of supernovae explosions and an even smaller amount of heavy elements the result of Neutron star collisions.

Yes, indeed.

https://en.wikipedia.org/wiki/Nucleosynthesis

[Iwonda (OP)]

Were these ices and metals just particles or were they sizeable chunks?

[chiralSPO]

Were these ices and metals just particles or were they sizeable chunks?

yes.

The various elements are produced by the nucleosynthesis mentioned earlier.

If the concentration of matter is high enough, and the temperature is low enough, the atoms (some may be ionized) can condense together to form molecules and nanoparticles, which can then aggregate or grow. The stability of these particles will be governed essentially by chemistry. Think of it as a grand-scale chemical vapor deposition. Or like how snow forms. Nucleation and growth.

If the conditions are right, specific substances may be favored. For example, once a particle is formed, it could be fairly highly selective for specific atoms to add on. The wrong atom type bounces off back into space more often than the right atom, and if the wrong atom does happen to attach, it is more likely to leave than the right atom (I am imagining a chemical equilibrium of sorts). In this way, especially if there is a locally high concentration of the right type of atoms compared to the wrong, we can imagine a mixture of elements condensing into particles of specific composition, as dictated by thermodynamics and the available matter.

Not too long ago, we observed the collision of two neutron stars, and researchers determined that about 10 earth masses of gold was produced from the collision. Now, it was sprayed over a fairly wide region of space, but gold also has a very high affinity for itself. I wouldn't be surprised if there were some gold grains and nuggets floating about!

[evan_au]

Minor planets (like the larger asteroids) which are massive enough to pull themselves into a spherical shape also probably have enough internal heat to melt the rocks at their core.

Gravity then causes the denser material (like iron and nickel) to fall to the center, while lighter materials like silicates farther out, and ices at the surface. This process is called "differentiation".
- Being much smaller than Mars, these bodies cool down in about 10 million years (fairly quickly in astronomical terms), and the iron core goes solid. The slow crystallisation produces distinctive crystal shapes called Widmanstätten patterns.
See: https://en.wikipedia.org/wiki/Widmanst%C3%A4tten_pattern

These large asteroids may then be demolished by collisions, producing iron meteorites.
- In 2022, there is a space probe planned for launch to the asteroid Psyche, which is believed to be the nickel-iron core of a minor planet.
See: https://en.wikipedia.org/wiki/16_Psyche

[Iwonda (OP)]

Wow, thanks a million for the great answers.