Old quantum theory

So, a long time ago there were some really smart people called physicists who wanted to understand how the world works. They studied things like light and atoms, and they came up with an idea called the "old quantum theory."

Now, imagine if the world was made up of tiny Lego blocks instead of just one big piece. That's sort of what atoms are like, they're made up of tiny pieces that are stuck together. These pieces are called electrons, and they move around the atom in specific paths called "orbits."

The physicists who came up with the old quantum theory noticed that sometimes when you shine light on an atom, an electron can jump from one orbit to another. This is kind of like if you're playing with your Lego blocks and you move one piece from one stack to another.

But here's where it gets a little confusing. The physicists noticed that sometimes the electron seemed to jump to a higher orbit without actually going through the space in between. It was like the electron teleported!

They didn't know exactly how this worked, but they came up with a rule called the "quantum condition" that explained when an electron was allowed to teleport like this. It's kind of like a rule saying you can only move your Lego blocks to certain other stacks depending on their size and shape.

So the old quantum theory was all about trying to figure out these weird things that were happening on a super tiny level. They didn't have all the answers, but they started to come up with new ideas that eventually led to our modern understanding of atoms and quantum mechanics!