What is quantum numbers in short

Big Bang 7, textbook

The modern atomic model 34 RG 7.2 G 7.2 Competence area atomic physics 75 What if the Pauli prohibition did not exist? Then all electrons would always be on the lowest shell, i.e. in the lowest energy state. Uranium, for example, the heaviest natural element, would then have all of its 92 electrons on one shell. The elements would lose their typical chemical properties (Section 34.5). All atoms could then combine with all atoms, and there would be no upper limit to the number of atoms in the molecules. Info: fermions and bosons In addition, without the Pauli ban, the elements would become smaller and smaller with increasing atomic number. Why? If there were only one shell, then with the increase in the number of protons in the nucleus, the electrical attraction would also increase and thus the orbitals would be drawn closer to the nucleus. This is actually the case, but only until a new s orbital has to be opened (Fig. 34.24; F13). The Pauli prohibition, together with the uncertainty principle, gives matter its volume! Summary Each quantum can be assigned a property called spin. The Pauli prohibition applies to quanta with half-integer spin (s = ± 1/2), such as electrons. Two electrons in the same orbital cannot have the same spin. This fact is absolutely necessary for an understanding of the period system. 34.5 Beyond Lithium The Periodic Table The chemical elements are shown in the periodic table. This regularity comes about through the possible energy states of the electrons. The periodic table can therefore only be understood in terms of quantum mechanics. To repeat briefly: A trapped electron can be described with the help of a standing probability wave. From this one can deduce the location of the electron, the orbital. In the one-dimensional case, the wave function looks like a vibrating string (Fig. 34.11, p. 70). In this simple case, only the wavelength can vary. Therefore, one can Z How do the elements of this universe differ, put simply? What are valence electrons? What is the maximum number of valence electrons an element can have? F16 E1 F17 W1 fully describe the one-dimensional case with only one quantum number. Info: Quantized energy -> p. 72 An electron in the atomic shell is also quasi “locked in” by the electrical attraction through the nucleus and can also be described by a standing probability wave. In this real, three-dimensional case, there are many more possibilities for variation, and the orbitals sometimes look quite strange. Table 34.2: Overview of the orbital shapes of the first 4 shells (K, L, M and N) for hydrogen: The quantum numbers n and l were varied, m is 0 in all cases. In contrast to Fig. 34.19 (p . 72) the representation here is three-dimensional. The colors indicate the phase of oscillation. Compare the 2p orbital in the third row in the second column with the vibrating soap lamella in Fig. 34.12 d, p. 70. Fig. 34.26: a) The principal quantum number n and the angular momentum number l determine the energy of the electron. b) “Intertwined” energy levels: With higher principal quantum numbers, the distances become smaller, and “irregularities” in the sequence occur. For example, an electron in the 4s orbital has less energy than in the 3d orbital. Hydrogen is an exception with only one electron. With him, the energy levels depend only on n, but not on l. For testing purposes only - property of the publisher öbv

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