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Chemistry LibreTexts

7: Quantum Atomic Theory

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  • Page ID
    98499
    • 7.1: The Discovery of Atomic Structure
      Atoms, the smallest particles of an element that exhibit the properties of that element, consist of negatively charged electrons around a central nucleus composed of more massive positively charged protons and electrically neutral neutrons. Radioactivity is the emission of energetic particles and rays (radiation) by some substances. Three important kinds of radiation are α particles (helium nuclei), β particles (electrons traveling at high speed), and γ rays.
    • 7.2: Electromagnetic Radiation
    • 7.3: The Quantum Nature of Light
    • 7.4: Quantization in the Atom
    • 7.5: Wave-Particle Duality
    • 7.6: The Quantum Mechanical Atom
    • 7.7: Atomic Orbitals
    • 7.8: Electron Configurations
      In addition to the three quantum numbers (n, l, ml) dictated by quantum mechanics, a fourth quantum number is required to explain certain properties of atoms. This is the electron spin quantum number (ms), which can have values of +½ or −½ for any electron, corresponding to the two possible orientations of an electron in a magnetic field. This is important for chemistry because the Pauli exclusion principle implies that no orbital can contain more than two electrons (with opposite spin).
    • 7.9: Building the Periodic Table
      The arrangement of atoms in the periodic table results in blocks corresponding to filling of the ns, np, nd, and nf orbitals to produce the distinctive chemical properties of the elements in the s block, p block, d block, and f block, respectively.