Looking into Atoms

Quantum physics is a branch of physics that works with the activities going on inside of atoms. They talk about subatomic particles interacting with each other. We're starting to talk about Albert Einstein and Max Planck's ideas here. In the early 1900's, scientists were beginning to examine the inside of atoms. They were wondering what was going on inside those things that were once thought to be solid. One big idea they came up with was that the energy of an electron depends on the frequency, or wavelength, of the EM Radiation. Another interesting idea they discovered was that energy didn't depend on the intensity, or amount, of radiation.

If you apply this idea to the structure of an atom, in the older, Bohr model, there is a nucleus and there are rings (levels) of energy around the nucleus. The length of each orbit was related to a wavelength. No two electrons can have all the same wave characteristics. Scientists now say that electrons behave like waves, and fill areas of the atom like sound waves might fill a room. The electrons, then, exist in something scientists call "electron clouds". The size of the shells now relates to the size of the cloud. This is where the spdf stuff comes in, as these describe the shape of the clouds.

Packets of Energy

During the early 1900's scientists also discovered that EM radiation not only moves like a wave, but has packs of energy (quanta) as well. It's like a stream of individual packets.

The Uncertainty Principle

A German scientist named Werner Heisenberg came up with this idea called the uncertainty principle. He figured that the position and momentum of an atomic particle cannot both be observed accurately at the same moment in time. The idea shows that because these pieces are so small, whatever device you use to measure the particles will affect them. Think about it. If you use light to examine a piece of light, won't you knock it around? Well now you just lost the idea of position. What if you freeze it in place? That's all very well, but now you don't know where it was going, or how much momentum it had. When you increase the precision of one measurement, the other measurement will suffer.

Look at the Heisenberg uncertainty principle in a more general way using the observer effect. While Heisenberg looks at measurements, you can see parallels in larger observations. You can not observe something naturally without affecting it in some way. The light and photons used to watch an electron would move the electron. When you go out in a field in Africa and the animals see you, they will act differently. If you are a psychiatrist asking a patient some questions, you are affecting him, so the answers may be changed by the way the questions are worded. Field scientists work very hard to try and observe while interfering as little as possible.

Next page on modern physics.
Return to Top of Page
Or search the sites for a specific topic.

Link to Cosmos4Kids.com Link to Biology4Kids.com Link to Chem4Kids.com Link to Geography4Kids.com Link to Physics4Kids.com Link to NumberNut.com Rader Network Side Navigation

What is a Proton? (Brookhaven Nat’l Labs Video)
Did you know? Physics Fact.

Physics Quiz

Modern Physics Quiz

Related Links

Physics4Kids: Radioactivity
Chem4Kids: Atoms
Chem4Kids: Atomic Structure
Chem4Kids: Isotopes
Geography4Kids: Energy Resources
Geography4Kids: Solar Radiation
Cosmos4Kids: The Sun
Cosmos4Kids: Stars

Physics4Kids Sections

Rader's Network of Science and Math Sites