Atomic Structure and Properties

• Light displays both particles and wave properties
• electromagnetic spectrum: the range of wave lengths or frequencies over which electromagnetic radiation extends
• when a substance is heated or electricity passes through, electrons in the atom absorb energy, causing electrons to jump to higher energy levels and fall back in specific intervals
• Bohr's model suggested the existence of energy levels and that each orbit corresponds to a state of constant energy called a stationary state (ground state)
• Bohr's model only explained one electron system
• Max Plank is the father of quantum theory. Suggested that matter can absorb or emit only discrete quantities of energy called a wuantum of energy
• Albert Einstein suggested that light was quantized.
• Photons: light that occurs as quanta of electromagnetic energy that have particle-like properties
• photoelectric effect: the release of electrons from a substance due to light striking the surface of a metal
• John Dalton is the father of modern atomic theory. He suggested that elements are composed of atoms. His model is the Billiard Ball Model
• Eugen Goldstein discovered canal rays which became known as the proton
• JJ Thompson discovered the electron. He calculated the charge to mass ratio for the electron. His model is the plum pudding model
• Max Planck suggested that energy from a blackbody is quantized
• Robert Millikan measured the charge of an electron from the oil drop experiment. He calculated the mass of the electron and the positively charged atom
• Ernest Rutherford suggested that atoms are mostly empty space. He suggested that atoms have a small, massive, positive nucleus and predicted the existence of neutrons. His model is the planetary model
• Niels Bohr suggested that electrons move in fixed orbits around the nucleus. His model is the solar system model
• Erwin Shrodinger showed that waved can be used to describe electrons in atoms. He determined the probability location of electrons in atoms. His model is the Quantum Mechanical Model
• James Chadwick discovered the neutron
• Electrons exist at certain energies and can move from one orbital to another
• electrons start in the ground state, move to excited states, then give off light when they return
• energies are increasing and decreasing
• quantum mechanics is a physical science dealing with the behaviour of matter and energy on the scale of atoms and subatomic particles and waves
• electron configuration: s<p<d<f
• 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6
• Aufbau Principle: Assumes the electrons are added to an atom one at a time starting with the lowest energy orbital until all of the electrons have been placed in an appropriate orbital
• Hunds Rule:

  • one electron is added to each of the degenerate orbitals in a subshell before two electrons are added to any orbital in the subshell.
  • electrons are added to a subshell with the same value of spin until each orbital in the subshell has at least one electron
• Pauli Exclusion Principle: No two electrons have the same 4 quantum numbers
• SP notation: listing of all the numbers and kinds of orbitals in increasing order
• Orbital box notation: listing in box form for the valence electrons only
• Kernal Notation: includes the noble gas that the element shares and a listing of the valence electrons
• Half filled and filled subshells make an atoms slightly more stable. When 3d subshells, with energies near those of 4s subshells are involved, the stability effect is large enough to allow the promotion of a 4s electron to the 3d subshell
• When elements lose electrons to become ions, they want to remain as stable as possible
• Louis de Broglie suggested that matter had a duel nature and electrons behave as both particles and waves
• Werner Heisenberg suggested that it is impossible to know the exact location and energy of an electron
• Erwin Schrodinger devised a type of mathematics called wave mechanics to account for the nature of electrons
• a wave equation describes the energy and motion of an electron around the nucleus. the solution to the wave equation is called the wave function
• quantum numbers are used to describe the energy of an electron in an atom
• Symbol: n

  • Principle quantum number
  • n=1,2,3,4,5...
  • describes the average distance the electron is from the nucleus (energy levels)
• Symbol: L

  • Secondary quantum number
  • l=n-1
  • 0(s), 1(p), 2(d), 3(f)
  • describes the path the electron follows/shape of the orbital
• Symbol: Ml

  • magnetic quantum number
  • Ml= -1...0...1
  • spacial orientation of the orbital