Why is lead denser than aluminum?

Question

Why is lead denser than aluminum?

Answer 1

Molecular structure!

Answer 2

aluminum is more porous, lighter, non ferrous material

Answer 3

Its atoms have more protons, neutrons and electrons in them which gives them more mass. They are larger in size as well, but the difference in size does not compensate for the difference in mass.

Answer 4

Lead has a much much more massive nucleus than aluminum for starters.  It is about ten times as massive as aluminum.  This makes the lead atom a bit larger, but not ten times larger, so the packing of the atoms in the crystal structure is not ten times less than the packing in aluminum.  As a result, lead metal has a higher density than aluminum metal.

Answer 5

The mass is determined simply by the masses of the nucleons and electrons.  But the volume is determined primarily by the electron shell configurations.  The details are a rather complicated matter of physical chemistry and quantum physics.  The ratio of their masses is 7.7 but the ratio of their densities is only 4.2.  I think the main difference is that the nature of the strong nuclear force permits lead to have a stable nucleus with many more neutrons than aluminum.