Why is bronze such a poor conductor of heat and electricity compared to other metals?


Iron, copper, and silver conduct both far greater than bronze. So why is it so bad at both compared to other metals?

In: 219

Bronze is made by mixing Copper with other things such as tin.

The property of Copper on it’s own is a good conductor of heat and electricity as you mentioned.

Now imagine changing it’s property in order to create something known as Bronze (which is an alloy).

This change in Copper’s structure will lose it’s ability in conducting heat and electricity comparatively.

Thus making Bronze a poor conductor at both compared to other metals.

The reason why copper is such a good conductor is that it has a lot of free movable electrons. They are not tightly bound to their atoms so they can move around and carry the energy with them.

When you mix tin in that will catch a bunch of those electrons and hold them in place.


Imagine you have some buckets with holes in them. Certain buckets have certain patterns of holes, so if you stack them together the water will still leak out quickly. Now imagine you stack two buckets together but the holes are in different places, so now it is hard for the water to find it’s way out.

The water is electricity, and the different types of buckets are different types of metal. Bronze is not one, but 2-3 metals mixed together.

My attempt:

Atoms join together in 3 main ways:

1. They attract like magnets [Ionic]
2. They hold hands (share electrons) [covalent]
3. They bear hug (smush together while their electrons go everywhere) [metallic]

The metallic bonds (bear hugs) are really good at conducting. Picture two lovers tightly embraced – their hands are free to wander wherever they want to – stroking, caressing, holding, carrying (heat and electricity) really well.

Metallic bonds are the default for pure metals, and because the atoms are just smooshed together the pure metals are very squishy, stretchy, and bendy (malleable, ductile, plastic).

When you combine different metals, things get complicated.

Bronze is made of Copper and Tin. Copper is a transition metal with really good metallic properties. Tin is a different kind of metal called a “post transition metal” and is in the same group as Carbon – so less good of a metal and very close to the semiconductor limit.

In fact, Cu & Sn are different enough that they no longer bear hug quite right. They hold hands AND bear hug. Their hands can still wander but they don’t quite have the ability to move heat and electricity that their pure states do. This additional rigidity also removes some of the metallic properties of the pure states, Bronze is less squishy, stretchy, and bendy than either Cu or Sn on their own.

On the other hand, Bronze *is* a better conductor than some steels, and that’s because steel contains a non-metal (Carbon) in its mixtures which moves its binding more towards hand holding with even less bear hug. This makes steel even stronger (but less conductive).

PS – even though Sn is in the same group as Carbon, Sn is still a metal, and that’s because the metals step their way into the non-metal space as we go down the periodic table. The larger the atom, the farther out the electrons are from the nucleus and the more they’re shielded by the inner electrons. This makes it easier for them to dissociate from the atom and join the “electron sea” of a metallic bond.

See [here](https://cdn.britannica.com/14/220014-050-7877CB9F/periodic-table-electron-configuration.jpg) for a periodic table. Copper is 29, Tin is 50. Element 51 (Antimony) is a semiconductor, Element 52 is considered a non-metal. Non-metals don’t do metallic bonds (bear hugs), only magnets and holding hands – so just a little bit of Tin changes the properties of the Copper base pretty radically.