In this video we explain the shell model in chemistry. ⬇⬇⬇More information and exercises can be found in the description⬇⬇⬇ All substances are made up of small particles. The smallest particles are atoms. What are atoms made of? An atom consists of an atomic nucleus that contains neutral neutrons and positively charged protons. The electrons are located around the atomic nucleus in the so-called atomic shell or electron shell, whose negative charges balance out the positive charges of the nucleus. The following is about the structure, i.e. the makeup of this atomic shell. You can find more videos and exercises on the structure of atoms here: https://learnattack.de/chemie/atomauf... Which shells are there in the atomic shell? Experiments have shown that the electrons in an atom are not all the same, but can be divided into groups depending on how much energy is needed to remove them from the shell. It was concluded that the atoms move around the atom in so-called shells - which can be imagined as similar to the different layers of an onion. The shell model has these laws: Firstly: the further a shell is from the nucleus, the less attractive the nucleus is and the easier it is to remove the electrons contained in it. Secondly: the further a shell is from the atom, the larger it is and the more electrons it can hold - according to the following scheme: the first shell, the K shell, can hold two electrons. the second, also called the L shell, can hold 8 electrons. the M shell, which is the third, can hold 18 electrons. the fourth shell, also called the N shell, can hold 32 electrons. It goes on like this, but that's enough for now. What are the inner shell and valence shell? This shell structure is the same for all atoms and elements. The only difference is how many electrons are filled into the shells. This is different for each element. The lowest shell is always filled first before the next one is tackled. The lower shells, which are already completely filled with electrons, are called the "inner shells". The shell into which an electron was last filled is called the outer shell or valence shell. It is particularly important because the number of electrons in the valence shell determines the properties of the corresponding atom. The shell model using sulfur as an example: Let's take the element sulfur as an example: It has 16 electrons. Of these, 2 electrons are in the first shell, 8 electrons in the second shell and 6 electrons in the third shell. The first and second shells are the inner shells, the third shell is the valence shell. Since there are six electrons in the valence shell, one would also say: "Sulfur has six valence electrons." A word about the validity of the shell model: The shell model is - as the word suggests - a model. That is, it is an image that describes reality - but only within certain limits. The shell model gives a good representation of the structure and behavior of the main group elements of the periodic table. However, it is not so clearly applicable to the so-called subgroup elements. A more advanced model, the so-called orbital model, helps here, but its explanation is much more complicated and not necessary at this point. Summary: The atomic shell is formed by different shells. Each shell can hold a certain number of electrons. The electrons are first filled into the lowest shells, closer to the nucleus. The shell into which the last electron was filled is called the valence shell. It is particularly important for the properties of the atom in question. Is something still unclear? No problem! Just post your question in the comments so that our chemistry professionals can help you! You can find more helpful explanations about the subject of chemistry on Duden Learnattack! We offer you: • interactive exercises • learning videos • class tests and corresponding sample solutions • step-by-step instructions Register now for free and prepare for your next class test without expensive tutoring. Register for free here http://www.learnattack.de/yt Like us on Facebook: / learnattack Follow us on Twitter: / learnattack Follow us on Instagram: / duden_learnattack Follow us on Google+: https://plus.google.com/+DudenLearnat... Follow us on Pinterest: https://www.pinterest.de/learnattack/