Atoms are not the smallest building block of matter.

In an historical sense atoms are a metaphor, since the term now refers to measurable, actual, and predictable entities that behave very unexpectedly, possess extraordinary power, are the source of electromagnetism, are comprised of smaller units called quarks that have spin, and manifest themselves as materials we variously called electrons, protons, neutrons and neutrinos with material energy or energetic matter that defies our convenient ideas about planets and the ballistics of objects that are made of millions of atoms.

But atoms are a clue to the patterns existing on the periodic table of atomic elements.

Radiation: the X-rays emitted by atoms pass right through our flesh to reveal the structure of our bones.

Instead of units of matter, these atoms are composites of neutrons or protons and electrons.

But a century after that shattering discovery of electrons surrounding a tight, massive and central core, atoms appear to be mostly empty space!

"Who knows what atoms yearn to be,

But we are all their progeny."

Ian McHarg

1917-2001

Ironically, hidden at the heart of all liquid, solid or vapor gas are elements made of atoms which are mostly empty space. All neutrons are the same heavy particle carrying no electrical charge.

The New York Times ran this sketch of what is believed about atoms after a century of experimental research.

emission of energy from an atomic nuclei

Neutrons are the origins of all atoms and are found in atomic nuclei of isotopes of hydrogen and most other elements. These neutrons can over time transform into a proton and an electron giving rise to radiation and hydrogen (H) nuclei. Atoms are important because they are both sources of enormous energy and a mortar of sorts that unify matter, as opposed to the smallest blocks that comprise the material, or physical world.

If a neutron and proton in a nucleus (of say heavy hydrogen) were the size of a medicine ball suspended above the ground, the nearly weightless electron cloud encircling the dense nucleus would be two to three miles away!

Even the hardest rock, or steel is composed of elements whose identical atoms are mostly empty space with an incredible electrical charge that accounts for how we perceive the surface of other materials. Long considered hard little billiard balls at the core of every material thing, atoms are instead made up of a more fundamental set of material.

This fundamental set of material, was named by Murray Gell Mann in the 1960s. He called "quarks" the building blocks of sub atomic particles. The quarks come in three pairs, so that there are six different quarks: Up, Down, Top, Bottom, Strange and Charmed.

Quarks are what give the mass to atomic nuclei, and the capacity of nuclei to lose neutrons and gain protons, thereby changing from one kind of atom into a more massive sister atomic element.

Hawking | Feynman | Kaku | about Bohr | Einstein

See Steve's terrific science web site