Introduction to Electronic Structure and Periodic Properties of Elements
In 1054, Chinese astronomers recorded the appearance of a “guest star” in the sky, visible even during the day, which then disappeared slowly over the next two years. The sudden appearance was due to a supernova explosion, which was much brighter than the original star. Even though this supernova was observed almost a millennium ago, the remaining Crab Nebula (see image below) continues to release energy today. It emits not only visible light but also infrared light, X-rays, and other forms of electromagnetic radiation.

The Crab Nebula consists of remnants of a supernova (the explosion of a star). NASA’s Hubble Space Telescope produced this composite image. Measurements of the emitted light wavelengths enabled astronomers to identify the elements in the nebula, determining that it contains specific ions including S+ (green filaments) and O2+ (red filaments). Image credit: modification of work by NASA and ESA
The nebula emits both continuous spectra (the blue-white glow) and atomic emission spectra (the colored filaments). In this tutorial, we will begin discussing light and other forms of electromagnetic radiation and how they are related to the electronic structure of atoms. We will also see how this radiation can be used to identify elements, even from thousands of light years away.
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Interesting
what is emission spectra and continous spectra.
There are two types of spectra: Emission spectra and Absorption spectra
Under Emission spectra is:
1. Line spectrum
2. Band spectrum
3. Continous spectrum: consists of radiation of different wavelengths of a heated body.
I hope you understand
what are electromagnetic radiation
Electromagnetic (EM) radiation is a form of energy that is all around us and takes many forms, such as radio waves, microwaves, X-rays and gamma rays. Sunlight is also a form of EM energy, but visible light is only a small portion of the EM spectrum, which contains a broad range of electromagnetic wavelengths. Cell phone transmissions are an example of how we use electromagnetic radiation. In the next set of lessons, you will learn more.