Topic 1

• Outer shell electronic configuration of p-block elements


  s2 p1 or s2p6
• Chromium and copper donate one of their 4s electrons to the 3d subshell because it is more stable with a full or half-full d subshell
• Configuration for s and p block ions up to Z = 36


  • Ca: 1s2 2s2 2p6 3s2 3p6 4s2
  • Ca2+: 1s2 2s2 2p6 3s2 3p6
• Classification of elements


  s, p, and d-block elements
• What electronic configuration determines

  The chemical properties of an element
• Electronic configuration of s-block elements

  1 or 2 outer shell electrons
• What s-block elements can easily do

  They can easily lose electrons to form positive ions with an inert gas configuration
• Electronic configuration of p-block elements

  1, 2, or 3 electrons can be gained to form negative ions with an inert gas configuration
• What happens when groups 4 to 7 share electrons

  They form covalent bonds
• What is special about inert gases in Group 0

  They have a completely filled s and p subshells and do not need to gain, lose, or share electrons
• What tends to happen with transition metals in the D block

  They tend to lose s and d electrons to form positive ions
• Periodicity


  The repeating pattern of physical or chemical properties across a period
• Bond strength across a period


  Metallic bonds get stronger across the period due to an increasing number of delocalized electrons and decreasing radii
• What determines the melting and boiling points of Na, Mg, and Al

  Metallic bonding and the increasing number of delocalized electrons
• Bonding in Si and its effect on melting/boiling point

  Si has a giant covalent lattice structure with many strong covalent bonds, resulting in a very high melting/boiling point
• What determines the melting/boiling points of P4(s), S8(s), and Cl2(g)

  The strength of London forces between their molecules
• Why sulfur has a higher melting/boiling point compared to others in its group

  Sulfur has more electrons, leading to stronger London forces and a higher melting/boiling point
• What is special about inert gases like argon

  They are monoatomic and have the lowest melting/boiling point due to very weak London forces
• Ionisation energy


  Given data or recall of the plots of ionisation energy versus atomic number
• The jump in ionisation energy between the 2nd and 3rd ionisation energies of an element is because the fifth electron is in an inner shell closer to the nucleus and attracted more strongly by the nucleus than the fourth electron
• Ionisation energy data provided

  • KJ 590 1150 4940 6460 8120 mol-1
• An element with a big jump between the 2nd and 3rd ionisation energies must be in group 2 of the periodic table
• Sub-atomic particles in an atom

  Protons, neutrons, and electrons
• Location of protons in an atom

  In the nucleus
• Relative charge of an electron

  • 1
• Relative mass of a neutron

  1
• Atomic (proton) number


  The number of protons in the nucleus
• Mass number


  The total number of protons and neutrons in the atom
• How to determine the number of neutrons

  By subtracting the atomic number from the mass number (Number of neutrons = A - Z)
• Isotopes


  Atoms with the same number of protons but different numbers of neutrons
• Relative isotopic mass


  The mass of one atom of an isotope compared to one twelfth of the mass of one atom of carbon-12
• Relative atomic mass


  The average mass of one atom compared to one twelfth of the mass of one atom of carbon-12
• Relative molecular mass


  The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12
• Relative formula mass


  The sum of the relative atomic masses of the atoms in the formula
• Purpose of mass spectrometry

  To determine the isotopes present in a sample and calculate the relative atomic mass of elements
• How to calculate relative atomic mass from relative abundance of isotopes


  R.A.M = (isotopic mass x relative abundance) / total relative abundance
• How mass spectrometry can determine relative molecular mass

  By measuring the m/z value for the molecular ion, M+
• Largest m/z peak in a mass spectrum


  It is due to the complete molecule and is equal to the relative molecular mass of the molecule
• Isotopes of chlorine


  • Cl35 and Cl37
• How to determine relative peak heights in mass spectrum of diatomic molecules like chlorine

  By expressing the relative abundances as decimals and calculating the ratios