atomic structure

• Details of the three Sub-atomic (fundamental) Particles

  • Particle
  • Position
  • Relative Mass
  • Relative Charge
• Proton


  • Nucleus
  • 1
  • +1
• Neutron


  • Nucleus
  • 1
  • 0
• Electron


  • Orbitals
  • 1/1800
  • -1
• An atom of Lithium (Li) can be represented as follows: 7 3 Li
• Atomic Number (Z)


  The number of protons in the nucleus
• Mass Number (A)


  The total number of protons and neutrons in the atom
• Number of neutrons


  A - Z
• Isotopes


  Atoms of same element with the same number of protons, but different numbers of neutrons
• Isotopes have similar chemical properties because they have the same electronic structure. They may have slightly varying physical properties because they have different masses.
• There are various models for atomic structure
• Relative atomic mass


  The weighted mean mass of one atom compared to one twelfth of the mass of one atom of carbon-12
• Relative Isotopic mass


  The mass of one isotope compared to one twelfth of the mass of one atom of carbon-12
• Calculating the Relative Atomic Mass of an Element

  1. R.A.M = (isotopic mass x % abundance) / 100

  2. R.A.M = (isotopic mass x relative abundance) / total relative abundance
• Relative molecular mass


  The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12
• Cl has two isotopes Cl35 (75%) and Cl37(25%)<br>Br has two isotopes Br79 (50%) and Br81(50%)
• These lead to the following spectra caused by the diatomic molecules
• Summary of most important ions to know

  • Group 1
  • Hydrogen
  • Silver
  • Gold
  • Ammonium (NH4+)<br>Group 2
  • Zinc
  • Copper (II)
  • Iron (II)
  • Tin
  • Lead<br>Group 3
  • Iron (III)<br>Group 5
  • Phosphate (PO4 3-)<br>Group 6
  • Carbonate (CO3 2-)
  • Sulfate (SO4 2-)<br>Group 7
  • Nitrate (NO3-)
  • Hydroxide (OH-)
• How to work out the formula from the ionic charge

  Identify the ionic charges of the two ions<br>2. Combine the ions together to get a neutral compound. i.e. combine so that the total +ve charge cancels out the total –ve charge
• Writing ionic equations


  Take full equation<br>2. Separate (aq) solutions into ions<br>3. Cancel out spectator ions leaving ionic equation