Structure 1.3 - Electron configuration

• Emission spectra are produced by atoms emitting photons when electrons in excited states return to lower energy levels.
• In the visible region, red light has the lowest energy, lowest frequency and longest wavelength. As we go across the spectrum, the energy and frequency both increase and the wavelength decreases. So violet light has the highest energy, highest frequency and shortest wavelength
• The lines in the emission spectrum converge at high energy, which corresponds to high frequency and short wavelength. So the distance between the blue and violet lines on the hydrogen emission spectrum is smaller than the distance between the red line and light blue line
• Continuous spectra


  Which spectrum is this?

  
• The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies.
• The main energy level is given an integer number, n, and can hold a maximum of 2n² electrons.
• The s sublevels contain one orbital
• The p sublevels contain three orbitals 
• The d sublevels contain five orbitals
• The f sublevels contain seven orbitals 
• Each orbital has a defined energy state for a given electron configuration and chemical environment, and can hold two electrons of opposite spin.
• Sublevels contain a fixed number of orbitals, regions of space where there is a high probability of finding an electron.
• The Aufbau principle states that when adding electrons to an atom, the lower energy orbitals must be filled first.
• The Pauli exclusion principle states that an atomic orbital can only hold two electrons and they must have opposite spins
• Hund’s rule states that when we have degenerate orbitals (orbitals of the same energy) then each orbital is filled with a single electron before being doubly occupied
• Define ionisation energy

  The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.
• In an emission spectrum, the limit of convergence at higher frequency corresponds to ionisation.
• Emission line spectrum


  Which spectrum is this?