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MrNobleGas t1_jc9qv70 wrote

As far as I'm aware, "arbitrarily many"

If this one introductory thermodynamics course I did last semester is any indication


hydroxypcp t1_jc9tx6k wrote

(orgchemist not physics one here) that sounds about right. If you start adding atoms, going 2, 3 etc there is no clear number when it suddenly behaves like a macroscopic solid. As with everything in science, "solid" is just a concept/model and there is no one 100% clear way to define when a set of particles switches from non-solid to solid

my thought process is: if we add Pb atoms and they stick together, then at what number do we consider it a solid particle? You wouldn't count alkane vapour where the molecules consist of dozens of atoms a solid (or liquid), right? In essence they are chemically bonded and stay together, so why would 20 or 30 Pb atoms together be considered differently? So what is it, 100, 200? It is pretty arbitrary

and it's not like if it's, say, 200 then at 199 it's not a solid and at 200 suddenly it is and behaves totally differently


Sharlinator t1_jcatjj1 wrote

How many grains of sand do you need before it can be called a heap?


GlassBraid t1_jcbg1ww wrote

I've heard an entertaining argument that the answer to your rhetorical question is zero. If there's a heap of sand and someone takes away one grain, there's still a heap of sand. If we repeat this many times, we have a heap of only one grain of sand, then remove that grain and have a heap of sand with no grains of sand left in it.


Putrid-Repeat t1_jcbh2oz wrote

Agreed with the others in that it is somewhat arbitrary as in the is no fixed number and it may vary with the element or molecule in question. But we usually consider it when the aggregate of atoms is relatively stable and has bulk properties of the solid. A gas or clump of atoms even of the same type likely will not behave as a solid of the same constituents.