Why is gold heavier than lead?

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SUMMARY

The discussion centers on the comparative densities of gold and lead, highlighting that despite lead nuclei being heavier (207 vs 200), gold is denser (19.31 g/cm³ vs 11.34 g/cm³). Both elements possess a face-centered cubic (FCC) crystal structure, which suggests similar packing efficiency. The key distinction lies in the atomic size, with gold atoms being smaller than lead atoms, leading to a higher density for gold. The terminology of "heavier" should be replaced with "denser" for clarity.

PREREQUISITES
  • Understanding of atomic structure and nuclear mass
  • Familiarity with crystal structures, specifically face-centered cubic (FCC)
  • Knowledge of density calculations and units (g/cm³)
  • Basic concepts of ionic radius and lattice constants
NEXT STEPS
  • Research the properties of face-centered cubic (FCC) crystal structures
  • Explore the relationship between atomic size and density in elements
  • Learn about the calculations of density and its implications in material science
  • Investigate the differences between atomic mass and density in various elements
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Students of chemistry, material scientists, and anyone interested in the physical properties of elements, particularly in understanding density and atomic structure.

kiskrof
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Not only are lead nuclei heavier than gold ones (207 vs 200), but the atoms are smaller (ionic radius 119pm vs 137pm). There is every reason for Pb to be heavier. Why is it lighter? (11.34 vs 19.31 g/cm^3)

They both have a FCC crystal structure, so the packing should be equally efficient.

Source: https://courses.edx.org/courses/course-v1:MITx+3.091x+3T2016/periodic_table/ (unfortunately, you probably need an edx account to visit)

Ignorance is lead, your answer will be gold to me. Thanks!
 
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Your question would be better phrased by replacing the word "heavier" with the word "denser". Try googling.
 
kiskrof said:
but the atoms are smaller

Not in a lattice they aren't. The lattice constant is not the ionic radius.