Why is Iron stronger than Gold?

[sbook2]

My little brother asked me and I can't seem to come up with an explanation. Any thoughts?

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[NextStepTutor_2]

Stronger? It all comes down to atomic structure. I'm a doctor not a physicist so I'll do my best.

The hardness of a material or metal is directly related to its atomic structure. Carbon comes in different forms. One is the graphite form of carbon in pencils. In graphite the carbon atoms are linked into hexagonal sheets. Between the sheets the forces are very, very weak. Diamonds, on the other hand (still pure carbon) have each carbon atom linked to 4 other carbon atoms forming a covalent bond. This bond is very, very strong .

Gold and Iron exhibit what is called metallic bonding. This is pretty weak and is related to the large nucleous of the atoms and the extended cloud of electrons surrounding the nucleus. Long story short, the forces between Au atoms in gold metal are quite weak and the electron clouds will drift more when compared to Iron. At least that's how I understand it. Not quire MCAT related but remember what makes all those transition metals so good for conducting electricity, being malleable, ductile, is that loose sea of electrons.

Hope this helps, good luck!

 

[sbook2]

Stronger? It all comes down to atomic structure. I'm a doctor not a physicist so I'll do my best.

The hardness of a material or metal is directly related to its atomic structure. Carbon comes in different forms. One is the graphite form of carbon in pencils. In graphite the carbon atoms are linked into hexagonal sheets. Between the sheets the forces are very, very weak. Diamonds, on the other hand (still pure carbon) have each carbon atom linked to 4 other carbon atoms forming a covalent bond. This bond is very, very strong .

Gold and Iron exhibit what is called metallic bonding. This is pretty weak and is related to the large nucleous of the atoms and the extended cloud of electrons surrounding the nucleus. Long story short, the forces between Au atoms in gold metal are quite weak and the electron clouds will drift more when compared to Iron. At least that's how I understand it. Not quire MCAT related but remember what makes all those transition metals so good for conducting electricity, being malleable, ductile, is that loose sea of electrons.

Hope this helps, good luck!

That was great, thank you!

 

[D2D]

Are you talking about pure Iron vs Gold or Steel/Cast Iron vs Gold?
Pure Iron is very soft... you can work it using a knife and hit it with a hammer into thin plates and draw it our into wires very easily.
Steel/Cast Iron on the other had is extremely hard because of the Fe-C bonds and the resultant structure.
If your little brother asked the question, I guess he must be referring to Steel/Cast Iron because it is very rare for someone to find Iron laying around at home.

 

[aldol16]

Are you talking about pure Iron vs Gold or Steel/Cast Iron vs Gold?
Pure Iron is very soft... you can work it using a knife and hit it with a hammer into thin plates and draw it our into wires very easily.
Steel/Cast Iron on the other had is extremely hard because of the Fe-C bonds and the resultant structure.
If your little brother asked the question, I guess he must be referring to Steel/Cast Iron because it is very rare for someone to find Iron laying around at home.

Even taking that into account, gold is still more malleable than iron. In fact, gold is the most malleable of all the metals so that difference can only be attributed to how easily the atoms in the lattice shift when struck.

 

[D2D]

Even taking that into account, gold is still more malleable than iron. In fact, gold is the most malleable of all the metals so that difference can only be attributed to how easily the atoms in the lattice shift when struck.

Of course it all has to do with the crystal structure.
Depending on whether we have compression or tensile loads there are other elements that are less strong than gold (e.g. platinum is more ductile). FCC structure in gold has more dof along compression loads, while CCP in platinum are more mobile when tensed.
But what I was alluding to is that the strength of the "Iron" the little brother may be talking about has more to do with the Fe-C bond more than the lattice structure of pure Iron.