Element properties.

To the 1st order, the valence shell makes the most significant contribution to the property of the atom and even the molecules it form. These shells are typically the ones that are involved in most chemical reactions and properties of the element.

However, when they form a solid, then there are other equally important factors involved, such as how they together form and arrange themselves in such a solid. Carbon atoms arranged one way becomes a brittle and even soft graphite. Arrange the same atoms in another way, and it becomes one of the hardest substance known, diamond. So the formation and properties of a solid just does not depend on the individual property of the atom.

Zz.

 

Molecular structure, how atoms are arranged, gives rise to most of the properties a substance exibits at the macro level. You need to do a little research on molecules to get a basic understanding of just how structure plays such an important role in defining properties of materials.

This will get you started: http://en.wikipedia.org/wiki/Molecules

 

For that, you have to open a solid-state physics text and learn about different types of crystal structures and why they cause differnt properties. A simple cubic structure, such as NaCl, for example, tends to be brittle and weakly bonded because each lattice ions are too far apart from each other. On the other hand, hexagonal closed pack configurations tend to be some of the hardest and strongest materials around since, by its name, each lattice ions are very tightly packed.

Zz.

 

Explore General Chemistry by Linus Pauling, one of the first to show how the electronic shell structure of atoms controls chemical bonding, for example. It's published by Dover, and is, at the very least, highly authoritative.
Regards,
Reilly Atkinson

 

But according to QM particles are an illusion. Also matter has other properties besides hardness. Electron configurations alone cannot account for all of them.

 

You can't really say that (unless you go to rather high-energy phenomena). CLASSICAL "bullet" particles are an illusion,but particles as "lumps of quantum numbers" do just fine in the quantum mechanics needed to explain matter properties.

This is right, but it is nevertheless amazing how much properties are explained based upon electron configuration alone. I'd say that about everything you consider matter properties on everyday scale fall into this class (if we are also allowed to use a few properties of the nucleus, such as mass and charge).
But, as you say, there are a few properties that aren't explained purely by electron properties. Nuclear magnetic resonance comes to mind. And of course all nuclear phenomena.