Question

why is a block of gold more dense than a block of iron of equal size

Answer 1

Because there is more mass per unit of volume:\[d=\frac{mass}{volume}\]

Answer 2

The gold nucleus has a much larger charge (+79) than the iron nucleus (+26), and furthermore many of its electrons are on orbits that do not shield outer electrons well. There are some relativistic effects as well, that serve to contract the size of the inner electron orbits. This all means that the electrons in a gold atom orbit much closer to the nucleus, so the gold atom actually ends up smaller (135pm) than the iron atom (140pm), even though it is almost four times heavier (because it has many more protons and neutrons in its nucleus).

In the solid state both gold and iron atoms are in close-packed array, but the much denser gold atom means solid gold is much denser than iron.

Answer 3

gold s heavy nucleus metal similarly leads nad silver is so these are heavier than the mass of same volume of iron. . .