What are the key atomic structures that make an atom metal or nonmetal?

Just wondering.
 

Mapes

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Metal atoms are distinguished by their low electronegativity, which characterizes the metallic bond (as opposed to the high-electronegativity covalent bond). A feature of the metallic bond is that the electrons are loosely held and participate strongly in electronic and thermal conductivity. In quantum mechanical terms, we would say that metals have a nonexistent band gap between the valence and the conduction bands, and the result is that electrons are easily excited to the conduction band.
 
What I was asking for was not the chemical properties that makes an atom metal or non-metal, but the structure of the atom that causes these properties.
 

Mapes

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Atoms with low electronegativity have one to several electrons in their outer shells.
 

DaveC426913

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What I was asking for was not the chemical properties that makes an atom metal or non-metal, but the structure of the atom that causes these properties.
Chemical properties is synomymous with atomic structure.

The chemical properties of an atom are entirely a result of the position of electrons in their shells.
 

olgranpappy

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It is not in general possible to say, based only on *atomic* properties, whether a solid will be a metal or a non-metal. Is solid hydrogen a metal or a non-metal? The naive answer (based on looking at the periodic table) is that solid hydrogen would be a metal. The actual answer is that in most circumstances solid hydrogen is not a metal.

The example of solid hydrogen is a little exotic. Even in the usual band picture of metals and insulators one can not simply look at the atomic properties. For example, just because a solid has an even number of electrons in the unit cell does *not* make it an insulator; if there are overlapping bands such a solid can still be a metal.

Whether or not a solid is a metal or insulator (in band theory) depends on both the atomic structure and the crystal structure (which determine band structure)... but certainly not just atomic properties. Cheers.
 
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can any element be made metallic if its compressed enough?
 
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If I'm not horribly confused about it, cosmologists (astrophysicists) classify anything heavier than He as a metal, since H and He are 'primordial', when it comes to star formation, and stars make 'metals'

Also, you can sort of map (there is a symmetry) between the concept of pure and mixed states in some ensemble - quantum or at the classical limit - to where a gas and a solid state are extremal as vertices in a graph, so all liquids are 'in-between' or mixed states of ensembles.

Any ensemble that is large enough (so approaches a significant fraction of Avogadro's N, of discrete 'states') exhibits 'metallicity', or the corresponding extremal state, or one that's a mixture.
Classical reality evolves from states that superpose, either at extreme vertices, or in between them.

Temperature, or heat which is mostly vibrational etc excitations of nuclei, is damped near 0K and ensembles then exhibit states which are ordered by a more fundamental set of rules, than the essentially chaotic thermodynamic background allows.
 

ZapperZ

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I think you need to re-read what olgranpappy has posted.

I can take Cu (which is a metal) and make Cu-O and it becomes completely an insulator. Or I can take carbon atoms, and in one arrangement I can make it into a "bad metal" like graphite, or turn it into a very hard insulator as diamond, without adding anything.

As Phil Anderson likes to say "More Is Different". The behavior of a solid is governed not by individual atoms, but rather by a collective property! This means that the collective behavior of the gazillion interactions, what we call the many-body physics, is what should be considered as the ground state.

Zz.
 

Mapes

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Also, you can sort of map (there is a symmetry) between the concept of pure and mixed states in some ensemble - quantum or at the classical limit - to where a gas and a solid state are extremal as vertices in a graph, so all liquids are 'in-between' or mixed states of ensembles.

Any ensemble that is large enough (so approaches a significant fraction of Avogadro's N, of discrete 'states') exhibits 'metallicity', or the corresponding extremal state, or one that's a mixture.
Classical reality evolves from states that superpose, either at extreme vertices, or in between them.
This sounds like a bunch of physics terms strung together into nonsensical sentences. (For example, a mole of silicon dioxide has far, far more than Avagadro's number of possible microstates, yet it is not a metal.) I can't imagine what scientific topics you might be referring to. Can you provide references?
 

LURCH

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If I'm not horribly confused about it, cosmologists (astrophysicists) classify anything heavier than He as a metal, since H and He are 'primordial', when it comes to star formation, and stars make 'metals'
Unfortunately, astrophysisists and chemical engineers use two different definitions for "metal." This has always been a source of some slight confusion, but I'm pretty sure the OP was talking about "metal" in the chemical sense, and not the astrophysical.
 
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Mapes said:
I can't imagine what scientific topics you might be referring to.
"Scientific topics" include the definition of a metal. Astrophysics is a science, therefore the term has more meaning than strictly the chemical one.

Stringing the terms extremal and mixed together wasn't too outrageous I thought.
So liquids can't possibly be a mixture of a solid and a gas state? Calling a solid 'extremal' needs references?
 

ZapperZ

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People seem to be forgetting another field in which the terms "solid, liquid, and gas" have been studied extensively, more than any other field of physics : condensed matter physics.

Zz.
 

Mapes

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"Scientific topics" include the definition of a metal. Astrophysics is a science, therefore the term has more meaning than strictly the chemical one.
I didn't dispute your first paragraph. I asked for references for this:

Also, you can sort of map (there is a symmetry) between the concept of pure and mixed states in some ensemble - quantum or at the classical limit - to where a gas and a solid state are extremal as vertices in a graph, so all liquids are 'in-between' or mixed states of ensembles.

Any ensemble that is large enough (so approaches a significant fraction of Avogadro's N, of discrete 'states') exhibits 'metallicity', or the corresponding extremal state, or one that's a mixture. Classical reality evolves from states that superpose, either at extreme vertices, or in between them.
It sounds like a personal theory, which is not appropriate for this forum.
 
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Ok, well obviously, there's no point in discussing what looks like personal theories.

The idea that solid and gas phases of matter are extremal vertices just doesn't gel, then.
 
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Conductivity is definitely a molecular property, as already written by others. Now, if you ask what makes a pure element a metal, no simple answer is correct neither...

The number of electrons in the outer shell isn't the whole picture. Sn is a metal, Ge and Si are semiconductors, and Si can be an insulator. But you may see a general tendency that high atomic numbers favour metals, as electrons are more weakly coupled to nuclei.

What chemists call metals (having an alkaline oxide) is also related to the strength of the electron-nucleus bond. Alkaline oxide is almost perfectly correlated with electricity conducting elements. Forget about astronomer's metals, it has no relationship.

As other contributors wrote, pressure can make an element metallic, so electronic structure doesn't tell everything...
 
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maybe metallic bonds make elements metallic
 

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