Thus, an excited electron has no option but to give off either 1 quanta or 2 quanta of energy, it cannot give up 1. Also, the electron can only move to very limited orbitals within the atom; it must end up in an orbital where the wavelength is now uses is "in phase" with itself.
These two restrictions limit the quality of the quanta of energy being released by the electron, and thus the nature of the photon of light that rushes away from the LED. Since the energy given off is strongly restricted to quanta, and quanta that allow the electron to move to a suitable place within the atom, the photons of light are similarly restricted to a tiny range of values of wavelength and frequency a property we see as "color".
Many LEDs have electrons that can only give up quanta of energy that, when converted into photons, produce light with a wavelength of about nm - which we then see as red light. These electrons are so restricted in the quanta they can emit that they never shine blue light, or green light, or yellow light, only red light.
Long, long before their were LEDs in our lives, scientists trying to understand electrons in atoms noted a similar phenomenon when light was either shone on certain materials or given off by certain materials. They used Bunsen's burner to strongly heat tiny pieces of various materials and minerals until they were so hot that they glowed and gave off light. Sodium, for example, when heated to incandescence, produced a strong yellow light, but no blue, green or red. Potassium glowed with a dim sort of violet light, and mercury with a horrible green light but no red or yellow.
When Kirchoff passed the emitted light through a prism it separated out into its various wavelengths the same way a rainbow effect is produced when white light is used , and he got a shock. He could only see a few thin lines of light in very specific places and often spread far apart. Clearly glowing sodium was not producing anywhere near all the different wavelengths of white light, in fact it was only producing a very characteristic band of light in the yellow region of the spectrum - just like a LED!
Kirchoff and Bunsen carefully measured the number and position of all the spectral lines they saw given off by a whole range of materials. These were called emission spectra , and when they had collected enough of them it was clear that each substance produced a very characteristic line spectrum that was unique.
No two substances produced exactly the same series of lines, and if two different materials were combined they collectively gave off all the lines produced by both substances. This, thought Kirchoff and Bunsen, would be a good way of identifying substances in mixtures or in materials that needed to be analyzed. So they did. In they found a spectrum of lines that they had never seen before, and which did not correspond to any known substance, so, quite rightly, they deduced that they had found a new element, which they called cesium from the Latin word meaning "sky blue".
Guess in what part of the spectrum they found the lines! All the research on atomic structure and the hideously difficult-to-understand properties of electrons come together in the topic of "electron energy".
An atom such as lithium has three electrons in various orbitals surrounding the atomic center. These electrons can be bombarded with energy and if they absorb enough of the quanta of energy being transferred they jump about and in the most extreme case, leave the lithium atom completely.
This is called ionization. Atoms can only bond if there is room to share or receive extra electrons on the outermost orbit of the atom. Electrons are also important to electricity. Electricity is basically the exchange of electrons in a stream called a current through a conducting medium.
In most cases the medium is an acid, metal, or similar conductor. In the case of static electricity, a stream of electrons travels through the medium of air. The understanding of the electron has allowed for a better understanding of some of the most important forces in our universe such as the electromagnetic force. Understanding its workings has allowed scientist to work out concepts such potential difference and the relationship between electrical and magnetic fields.
We have written many articles about electrons for Universe Today. Listen here, Episode Inside the Atom. Sources: Wikipedia Windows to Universe. An atom is in balance when it has an equal number of protons and electrons. The neutrons carry no charge and their number can vary. The number of protons in an atom determines the kind of atom, or element , it is. An element is a substance consisting of one type of atom. The Periodic Table of Elements shows elements with their atomic numbers—the number of protons they have.
For example, every atom of hydrogen H has one proton and every atom of carbon C has six protons. Electrons usually remain a constant distance from the atom's nucleus in precise shells. The shell closest to the nucleus can hold two electrons. The next shell can hold up to eight. The outer shells can hold even more. Some atoms with many protons can have as many as seven shells with electrons in them. The electrons in the shells closest to the nucleus have a strong force of attraction to the protons.
Sometimes, the electrons in an atom's outermost shells do not have a strong force of attraction to the protons. These electrons can be pushed out of their orbits. Applying a force can make them shift from one atom to another. These shifting electrons are electricity.
Lightning is a form of electricity. Lightning is electrons moving from one cloud to another or electrons jumping from a cloud to the ground. Have you ever felt a shock when you touched an object after walking across a carpet? A stream of electrons jumped to you from that object. This is called static electricity. Have you ever made your hair stand straight up by rubbing a balloon on it? If so, you rubbed some electrons off the balloon.
The electrons moved into your hair from the balloon. The electrons tried to get far away from each other by moving to the ends of your hair. They pushed against or repelled each other and made your hair move.
Just as opposite charges attract each other, like charges repel each other. Electricity explained The science of electricity.
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