periodicity

• what is ionisation?


  the removal of an electron from an atom to make a positive ion (cation)
• what is the atomic radius?


  distance between the nucleus and outermost electron of an atom
• what is the trend of atomic radius across a period?


  decreases

  nuclear charge increases

  electron shielding is similar

  attraction between nucleus and outermost electron increases

  electrons are closer to the nucleus
• what is the trend of atomic radius down a group?


  increases

  outermost electron is further from the nucleus

  electron shielding increases

  more complete energy levels
• what is first ionisation energy?


  enthalpy needed to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of unipositive ions
• what is the first ionisation energy equation?


  X(g) --> X+(g) + e-
• what is the trend of first ionisation energy down a group?


  decreases

  outermost electron is further from the nucleus

  electron shielding increases

  more complete energy levels

  attraction between nucleus and outermost electron decreases

  less energy is required to remove outermost electron
• what is the general trend of first ionisation energy across a period?


  increases

  nuclear charge increases

  atomic radius decreases

  outermost electron is closer to the nucleus

  similar electron shielding

  attraction between nucleus and outermost electron increases

  more energy required to remove outermost electron
• why is there a deviation at group 3?


  contains p1 electrons

  electrons have entered new subshell

  higher in energy

  less energy required to remove outermost electron
• why is there a deviation at group 6?


  contains p4 electrons

  pair of electrons in orbital which repel

  less energy required to remove outermost electron
• what are successive ionisation energies?


  enthalpy changes for reactions where electrons are successively removed from an atom
• what is the second ionisation energy equation?


  X+(g) --> X2+(g) + e-
• what is the third ionisation energy equation?


  X2+(g) --> X3+(g) + e-
• what is the successive ionisation energy trend?


  increases

  outermost electron is closer to nucleus

  ionic radius decreases

  outermost electron being removed from an ion with more protons than electrons

  attraction between nucleus and outermost electron increases

  more energy required to remove outermost electron
• what does a large jump in IE represent?


  an electron being in an energy level closer to the nucleus
• which will have a higher IE: isoelectronic atom or ion?


  species with greater nuclear charge

  similar electron shielding

  more energy required to remove outermost electron
• which will have a higher IE: two species electron configuration p6 and s1?


  species with p6 subshell

  electron in energy level closer to nucleus

  less electron shielding

  more energy required to remove outermost electron
• which will have a higher IE: two species moving along a subshell?


  species further along subshell

  greater nuclear charge

  similar electron shielding

  more energy required to remove outermost electron
• which will have a higher IE: two species electron configuration s2 and p1?



  species with electron configuration s2

  p1 deviation -

  new subshell at higher energy level

  similar electron shielding

  less energy required to remove outermost electron
• which will have a higher IE: two species electron configuration p3 and p4?



  species with electron configuration p3

  p4 deviation -

  spin pair repulsion

  less energy required to remove outermost electron
• which will have a higher IE: successive ionisation of same element?


  higher ionisation

  more energy required to remove electron from positive ion

  smaller ionic radius

  greater attraction between nucleus and outermost electron

  more energy required to remove outermost electron
• which will have a higher IE: two species in same group?


  species higher in group

  electron removed from energy level closer to nucleus

  less electron shielding

  more energy required to remove outermost electron
• what is the melting point of a substance?

  temperature solid becomes liquid
• what is the boiling point of a substance?

  temperature liquid becomes gas
• what is the trend in melting point along period from Na to Al?

  1. increased melting point
  2. higher charged positive ions and more delocalised electrons
  3. stronger attractions
• what is the trend in melting point along period 3 for Si?

  1. has giant covalent structure
  2. many strong covalent bonds to be broken
  3. highest melting point of the period
• what is the trend in melting point along period 3 for P,S,CL,Ar?

  1. S8>P4>Cl2>Ar1
  2. melting point increases the size of molecule increasing
  3. stronger Van der Waals forces
  4. larger molecules have more electrons
  5. larger molecules have greater surface area
• elements from which group will have the highest melting point of a period?

  group 4