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