Why is platinum heavier than gold when used to make a ring?

[abefroman]

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[ChemGeek]

Oh this is right up my alley!! I don''t work with metals, and haven''t studied them in a while, but I''ll give this a shot since I haven''t worked with densities, periodic tables, etc...since undergrad (I work in pharma now...much different!) and my gen. chem book is actually out in my car right now... but I''ll see what I can come up with. Most of what has been said already is right on, though.

Density of Platinum = 21400 kg/m^3 (21.4g/cm^3)
Density of pure gold = 19320 kg/m^3 (19.32 g/cm^3) (random FYI: a sqare foot of gold weighs over a thousand pounds!)

And yes, the more pure it is, the heavier it is, so since gold is usually some sort of alloy, this would make it much lighter than a platinum alloy.

Then you have the electron oribitals (which have also already been mentioned) and yup, each has one valence electron, and there is also metallic bonding which gives metals their unique properties of malleability and conductivity. Metallic bonding is caused by the electromagnetic interaction between delocalized electrons.

That''s about all I can say without getting overly complicated and getting into some stuff that even I have no clue about (physical chemistry and quantum mechanics...AAAACK!!!

)

So yeah, it all boils down basically to how pure it is, and how closely packed the atoms can be in a given element.

 

[abefroman]

Date: 8/26/2009 10:04:04 AM
Author: ChemGeek
Oh this is right up my alley!! I don''t work with metals, and haven''t studied them in a while, but I''ll give this a shot since I haven''t worked with densities, periodic tables, etc...since undergrad (I work in pharma now...much different!) and my gen. chem book is actually out in my car right now... but I''ll see what I can come up with. Most of what has been said already is right on, though.


Density of Platinum = 21400 kg/m^3 (21.4g/cm^3)

Density of pure gold = 19320 kg/m^3 (19.32 g/cm^3) (random FYI: a sqare foot of gold weighs over a thousand pounds!)


And yes, the more pure it is, the heavier it is, so since gold is usually some sort of alloy, this would make it much lighter than a platinum alloy.


Then you have the electron oribitals (which have also already been mentioned) and yup, each has one valence electron, and there is also metallic bonding which gives metals their unique properties of malleability and conductivity. Metallic bonding is caused by the electromagnetic interaction between delocalized electrons.


That''s about all I can say without getting overly complicated and getting into some stuff that even I have no clue about (physical chemistry and quantum mechanics...AAAACK!!!

)


So yeah, it all boils down basically to how pure it is, and how closely packed the atoms can be in a given element.

Thanks! That makes sense.

I got a pretty good shock when I got the bill for my custom ring, I was expecting the platinum to only cost about 1.3 times the cost of white gold, when it was actually about 2.6 times the cost.