MODULE 1: Q2

• Electronic Structure of Matter


  The arrangement of electrons in an atom
• Joseph John Thomson conducted an experiment using the cathode ray tube
• His experiments resulted in the discovery of the electron
• Nuclear model of the atom


  Thomson's atomic model
• Different colors of flame during fireworks are due to different metallic elements
• Different metallic elements release different amounts of energy when heated

  This is because of the excited electrons
• Wavelength


  The distance between two successive crests
• Amplitude


  The height of the wave
• The shorter the wavelength

  The higher the energy
• A glass prism can be used to separate the components of light
• The white light from the sun produces different colors of the spectrum
• Flame test


  Identify elements and the energy produced
• Name of elementsWith their Colors:

  • Sodium -Yellow
  • Copper- green
  • Lithium- light red
  • Lead- pale blue
  • Calcium- brick red
• Niels Bohr explained that each atomic spectra of elements indicates the transformation of energy within the atom
• Energy level


  Fixed energy where electrons move around the nucleus
• Each main energy level in an atom consists of sublevels
• When the electron is on its ground state there is an absorption of energy
• As the electron goes back to its original energy level, it will release energy
• Main Energy Levels

  • 1 or K
  • 2 or L
  • 3 or M
  • 4 or N
  • 5 or O
  • 6 or P
  • 7 or Q
• Sublevels

  • s
  • p
  • d
  • f
• Heisenberg’s Uncertainty Principle states that it is not possible to determine the exact location and velocity of an electron in an orbital at the same time
• Electron cloud


  The region composed of negatives surrounding the nucleus associated with the atomic orbital
• Quantum Mechanical Model


  Introduced by Schrodinger, shows how likely an electron can be found around the nucleus
• The Quantum Mechanical Model describes the region of space around the nucleus as consisting of shells
• Principal Energy Levels and Sublevels of Electrons

  • 1
  • 2
  • 3
  • 4
  • 5
• Principal quantum number (n) describes the energy level of an electron in an atom
• Angular Momentum Quantum Number (l)


  Describes the way electrons move around the nucleus and determines the shape of an orbital
• Orbital types

  • S orbital (l = 0)
  • P orbital (l = 1)
  • D orbital (l = 2)
  • F orbital (l = 3)
• Magnetic Quantum Number (ml)


  Refers to the possible behavior of the electrons in a magnetic field
• Spin Quantum Number (ms)


  Describes the rotations or spins of electrons as they move around the nucleus
• The electron spinning clockwise has the - ½ values
• The electrons that are spinning counter-clockwise have the + ½ values
• Quantum Numbers

  • Principal quantum number
  • Angular Momentum Quantum Number
  • Magnetic Quantum Number
  • Spin Quantum Number
• The Aufbau Principle requires that the electrons occupy the lowest possible energy level before filling up the next
• Pauli’s Exclusion Principle states that no two electrons can have the same set of four quantum numbers
• Hund’s Rule requires that the electrons fill the orbitals in a sublevel, one by one, before pairing the electrons
• Electron configuration can identify information about the elements in terms of group number, period number, number of paired and unpaired electrons, and valence electrons