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Chemistry LibreTexts

8: Electronic Structure

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  • Atoms act the way that they do because of their structure. We already know that atoms are composed of protons, neutrons, and electrons. Protons and neutrons are located in the nucleus, and electrons orbit around the nucleus. But knowing structural details is key to understanding why atoms react the way they do. Virtually everything known about atoms ultimately comes from light. Before the composition of atoms (especially electrons) can be understood, the properties of light need to be understood.

    • 8.0: Prelude to Electronic Structure
      A startling conclusion of modern science is that electrons also act as waves. However, the wavelength of electrons is much, much shorter—about 0.5 to 1 nm. This allows electron microscopes to magnify 600–700 times more than light microscopes. This allows us to see even smaller features in a world that is invisible to the naked eye.
    • 8.1: Light
      Light acts like a wave, with a frequency and a wavelength. The frequency and wavelength of light are related by the speed of light, a constant. Light acts like a particle of energy, whose value is related to the frequency of light.
    • 8.2: Quantum Numbers for Electrons
      Electrons in atoms have quantized energies. The state of electrons in atoms is described by four quantum numbers.
    • 8.3: Organization of Electrons in Atoms
      The Pauli exclusion principle limits the number of electrons in the subshells and shells. Electrons in larger atoms fill shells and subshells in a regular pattern that can be followed. Electron configurations are a shorthand method of indicating what subshells electrons occupy in atoms. Abbreviated electron configurations are a simpler way of representing electron configurations for larger atoms. Exceptions to the strict filling of subshells with electrons occur.
    • 8.4: Electronic Structure and the Periodic Table
      The arrangement of electrons in atoms is responsible for the shape of the periodic table. Electron configurations can be predicted by the position of an atom on the periodic table.
    • 8.5: Periodic Trends
      Certain properties—notably atomic radius, IE, and EA—can be qualitatively understood by the positions of the elements on the periodic table.
    • 8.E: Electronic Structure (Exercises)
      These are exercises and select solutions to accompany Chapter 8 of the "Beginning Chemistry" Textmap formulated around the Ball et al. textbook.