Topic 2 – Dalton’s Atomic Theory

The Evolution of the Atom

This shows the evolution of the model of the atom. It begins at top left with Dalton’s idea of an indivisible particle and moves to the left until Bohr’s model appears in the lower left. Bottom right is a modern representation.

Last time, I introduced the atomic nature of the physical universe. This time we will look a little deeper at its roots.

The history of chemistry goes back thousands of years, probably starting with the alchemists, and it’s interesting. The alchemists might be among the greatest con men of all time. That period in the development of science is a great story for another time.

When thinking about atoms, we start much later in history, with the work of John Dalton who contributed the major portion of his work around 1800. His model of the structure of matter marks the beginning of modern chemistry and while today, we know he missed the mark on a couple of his assertions, his basic model still serves as a simple way to understand much of the physical universe. Continue reading

Topic 1 – The Atomic Nature of the Physical Universe

An atom with its orbitals showingIf you take a moment to look around you, it’s a gorgeous world.  Every single thing you see that is solid has a shape, and the liquids and gases swirl and wave in ways that are wonderful to watch.  The macroscopic world is not only beautiful but it is functional.  The shapes, sizes and colors have function and meaning and in most cases, purpose.

But even the young school children know something like a tree is not one solid piece.  There are at the very least, bark, leaves and branches.  Right now if you look around wherever you are, you will probably easily notice that most things are made of pieces.  As I write, I am at my desk and in front of me I see pens, my computer screens and a couple of speakers.  The pens have caps and clips and I know inside I will find a thin pipe and inside that I will find ink.  The screens have a variety of plastic pieces all with different purpose and I know there are circuit boards and wires inside.  The speaker has a variety of buttons and knobs and the different kinds of materials are obvious.  Without really thinking about it, we see a pen, a screen and a speaker – the whole – but upon closer inspection, most things can be decomposed into parts.   Continue reading