Atomic Structure | Universe Today

Written by Jean Tate

Are atoms composed of smaller things? Do atoms have structure? From when Dalton proposed the scientific theory that matter is composed of atoms, at the start of the 19th century, exactly these questions have been asked … and many scientists tried to answer them …

Today, a lot of people have the idea that atomic structure is like the solar system, with the atomic nucleus as the Sun, and electrons as planets in orbit around the nucleus; this is the Rutherford atom, or perhaps the Bohr atom … well, if you regard science as, among other things, a set of tools to test ideas like this, then the Rutherford atom does not describe atomic structure (or at least not consistently).

Today, the best description of atomic structure is one totally dependent on the mathematics of quantum mechanics. And what follows from this? Well, for one thing, any 'word picture' description of atomic structure will be at least somewhat inaccurate, if not downright misleading!

So, yes, the nucleus contains the protons and neutrons, occupies a tiny fraction of the volume of the atom (but contains nearly all its mass), and within the nucleus the protons and neutrons have some sort of energy-based distribution (but how to explain it?).

And yes, the electrons are structured into 'shells' (which are also somehow related to energy), but can be described as being probability clouds, with odd shapes! Oh, and the electrons themselves have no size, but have 'spin' (which is quite unlike the spin of a spinning wheel), and …

Yet all this mind-twisting quantum-mechanics-based-view of atomic structure works superbly well, in the sense that you can explain all of chemistry, all of atomic physics, all of … with it!

I guess the universe is under no obligation to be easily comprehensible to us (at least so far as atomic structure is concerned).

Atomic structure is covered in a LOT of teaching material; for example Structure of the Atom (New York University), Atomic Structure Timeline (a high school project!), and Atomic Structure of Matter (NASA).

New Study Finds Fundamental Force Hasn't Changed Over Time is a Universe Today story quite relevant to atomic structure (can you see why?). And here's a challenge: what's the atomic structure of Copernicium? (HINT: check out the Universe Today story Welcome "Copernicium", Our Newest Element).

Two Astronomy Cast episodes for you: Inside the Atom, and The Important Numbers in the Universe.

Filed under: Astronomy