Copper and silver - why the best conductivity?

What is it about copper that makes it so good as a conductor of heat?

Similar q. for silver and electricity.

Reply to
jtaylor
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Chemistry and valence electrons. Gold also. Do a google for "conductors".

Reply to
Robert Swinney

Welcome to the world of physics and quantum mechanics! You might try reading this:

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or this:
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or possibly even this:
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Reply to
Carmine Castiglia

I think he was asking why thermal and electrical conductivity tend to go hand-in-hand.

The answer is that head is carried by two mechanisms in materials, by phonons and by conduction electrons. Things that have highly mobil conduction electrons also conduct heat very well.

Alloys have built-in impurity sites so both the conduction electrons and the phonons get scattered.

There are some interesting materials like sapphire (see another thread here) that exhibit no electrical conductivity, but very, very large thermal conductivity. At some temperatures it approaches that of copper.

Now someobody has to explain whey copper is red and gold is, well, gold-colored.

Jim

Reply to
jim rozen

And, while we're at it, if you pound gold thin enough so that you can see through it, it's blue...

Jerry

"conductors".

Reply to
Jerry Foster

Copper, Silver and Gold are in the same column of the chemical element chart. (same free electron count)

In general Hyper physics states :

The general properties of metals include malleability and ductility and most are strong and durable. They are good conductors of heat and electricity. Their strength indicates that the atoms are difficult to separate, but malleability and ductility suggest that the atoms are relatively easy to move in various directions. The electrical conductivity suggests that it is easy to move electrons in any direction in these materials. The thermal conductivity also involves the motion of electrons. All of these properties suggest the nature of the metallic bonds between atoms.

Remember - the larger the atom - the further away the outer shell is from the center. They are in weak control and are available to move or swap. They can easily move up/down shells and on/off from atom to atom.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

jtaylor wrote:

Reply to
Martin H. Eastburn

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

jim rozen wrote:

Reflection and absorption. Martin

Reply to
Martin H. Eastburn

Atomic Physics. What wavelength will pass through - and what will be absorbed. Short UV and blue can pass. Sneaking through the pickets of electrons while the Red is absorbed as energy.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Jerry Foster wrote:

Reply to
Martin H. Eastburn

Purple, actually. Colloidal gold.

Harold

Reply to
Harold and Susan Vordos

Ah but aluminum reflects and absorbs light too - it does so evenly across the spectrum. What's so special about, say, copper, that causes it to reflect more of the red. Something special is going on there.

Jim

Reply to
jim rozen

Yep. Has something to do with the plasma frequency...

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page, and particle physics if you dare.

Tim

-- Deep Fryer: a very philosophical monk. Website:

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Reply to
Tim Williams

"Why is a penny red?"

That child's question could not really be answered until a very few years ago.

Ignoring the fact that pennies aren't much copper anymore....

Jim

Reply to
jim rozen

First of all let us not think that everything that reflects has 100% of the color and image that came into it to be reflected. You seem to think this way.

All elements have distinctive burn colors and absorbs and reflects based on the atomic model.

Chrome is blue when done over steel - it is not all that cool looking. When copper is plated on the steel and then the copper is chromed the color is shifted to the white.

This is a very complex line of work. Paints, inks and glass all requires real knowledge. Ever have yellow shooting glasses ? See yellow and high contrast. Knocks out the UV that is fuzzy.

I don't think Al reflects and absorbs evenly across the spectrum - that would be really ODD.

Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

jim rozen wrote:

Reply to
Martin H. Eastburn

Atomic absorption and emission (from flame spectra, like you are discussing now) are very different than the optical effects from metals reflecting incident light. Flame spectroscopy like that can be done on non-metals.

Actually it pretty much does. If you were to look at a reflection spectrum from a metal like aluminum, where the fermi level is such that there are plenty of electrons to respond to the incident wave, you find that there's a pretty flat response in the visible. It does fall off in the UV and the IR.

Jim

Reply to
jim rozen

Jim -

Can you tell me the number of that perfect Al ?

2xxx contains copper 2xxx contains copper and Mg 6xxx contains mg and Si 7xxx contains Zn and Mg 7xxx contains Zn, Mg, Cu 5xxx contains Mg 3xxx contains Mn 4XXX contains Si 1xxx is ?pure more or less ?

I think you generalized to make your point.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

jim rozen wrote:

Reply to
Martin H. Eastburn

Most mirrors are made with *pure* aluminum, there is no alloying agent used. The stuff on my shelf is 5/9s IIRC.

Jim

Reply to
jim rozen

I agree mirrors are sputtered Aluminum or sheet silver or my gaudy sheet gold :-) The glass is typically, not always by any means a safety glass with an index of refraction and absorbs producing defects.

In camera lenses they use rare earth glass to limit distortion. I don't think any of us could afford a half-length hallway mirror in rare earth materials.

To the eye it is close enough or fine enough to use. Some are better. Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

jim rozen wrote:

Reply to
Martin H. Eastburn

The best mirrors are so-called "first surface" mirrors, where there is no glass between the incoming and outgoing waves. The metal is on the *front* of the glass.

A close inspection of the average bathroom mirror shows *two* images - one from the indident wave being reflected off the interface between the glass and the air, and the stronger one from the metal to the glass interface. Very annoying.

After accidentally smashing my truck side-view mirror, I found that it was indeed first surface - and the one the glass folks tried to install was not. The replacment performed poorly.

Jim

Reply to
jim rozen

really? front surface mirror scratches REALLY easily. even handling it gently when i make kalidiscopes and attempting to clean it leaves scratches. was there any protection on the front of it to protect the metal surface?

regards, charlie

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Reply to
Charles Spitzer

Nope, just an aluminized first surface mirror. No coatings, nothing fancy. It held up pretty well - until that lady in the jaguar crossed over the line one day, and our mirrors collided. I think she wound up paying more for hers, than I did for mine.

:^)

Jim

Reply to
jim rozen

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