5.2: electronic structure of atoms and electron conficurations

the wave nature of light

• light (electromagnetic radiation) has wave-like properties and is characterized by wavelength, frequency, and speed
    * electronic structure: the structure of electrons within atoms
      * our understanding of electronic structure comes from analyses of light emitted and absorbed by substances
    * electromagnetic radiation: radiant energy
      * eg. visible light
    * wavelength (λ): the distance between two adjacent peaks (tops) or troughs (bottoms) of a wave
    * frequency (v): the complete number of wavelengths (“cycles”) that pass a given point each second

quantized energy and photons

• electromagnetic radiation also has particle-like properties and can be described as photons, or “particles” of light
    * quantum: the smallest quantity of energy that can be emitted or absorbed as electromagnetic radiation
    * Planck constant: constant h; 6.62 x 10^-34 joule-seconds
    * photoelectric effect: the application of Planck’s theory; posits that a minimum frequency of light is required for the emission of electrons
    * photon: a particle of energy light
• E = hv
• energy of photon = Planck constant x frequency

line spectra and the Bohr model

• we examine the light emitted by electrically excited atoms (line spectra)
    * spectrum: produced when radiation is separated into different component wavelengths
    * line spectrum: a spectrum containing radiation of only specific wavelengths
    * principle quantum number: the integer h in Bohr’s model (formula)
    * ground state: the lowest-energy state of an atom
    * excited state: higher-energy states of an atom (n ≥ 2)

the wave behavior of matter

• matter also has wave-like properties
    * matter waves: wave characteristics of material particles
    * momentum: the quantity mv (mass x velocity) of any object
    * Heisenberg’s uncertainty principle: posits that it is impossible for people to know simultaneously the exact momentum of an electron and its exact location in space

electron configurations

the afbau principle

• afbau is german for “building up”
• states that protons are added one by one to the orbitals of atoms
• valence electron: an electron located in the highest occupied principle energy level