QUANTUM CHEMISTRY

• HEISENBERG UNCERTANITY PRINCIPLE?

  • impossible to determine simultaneously both the position and velocity of an electron/ any other particle
• PAULI EXCLUSION PRINCIPLE?

  • number of electrons to be filled in various orbitals is restricted
  • only two electrons can occupy same orbital
  • must have opposite spins
• HOW MANY ELECTRONS CAN OCCUPY ORBITALS 1s, 2s, 3s and 4s?

  2
• HOW MANY ELECTRONS CAN OCCUPY ORBITALS 2p, 3p and 4p?

  6
• HOW MANY ELECTRONS CAN OCCUPY ORBITALS 3d and 4d?

  10
• HOW MANY ELECTRONS CAN OCCUPY ORBITAL 4f?

  14
• HUND'S RULE OF MAXIMUM MULTIPLICITY?

  in a sublevel, each orbital is singly occupied before it is doubly occupied
• AUFBAU PRINCIPLE?

  electrons fill lower energy atomic orbitals before filling higher ones
• PRINCIPLE THAT STAES THE POSITION AND VELOCITY CANNOT BE MEASURED AT THE SAME TIME?

  Heisenberg Uncertainty Principle
• PRINCIPLE THAT STATES THE NUMBER OF ELECTRONS IN VARIOUS ORBITALS IS RESTRICTED?

  Pauli Exclusion Principle
• PRINCIPLE THAT STATES EACH SUBLEVEL MUST BE SINGLY OCCUPIED BEFORE IT IS DOUBLY OCCUPIED?

  Hund's Rule of Maximum multiplicity
• PRINCIPLE THAT STATES ELECTRONS FILL LOWER ENERGY ORBITALS BEFORE HIGHER ONES?

  Aufbau Principle
• WHY IS THE FIRST IONISATION ENERGY OF Al LESS THAN THE FIRST IONISATION ENERGY OF Mg?

  • Al electron in 3p
  • Mg electron in 3s
  • Energy of 3p is greater than 3s
• HOW DO YOU DETERMINE AN ELEMENT'S BLOCK?

  highest energy/ outer orbital letter
• WHY DOES IONISATION ENERGY OF Al DEVIATE FROM THE GENERAL TREND?

  e- removed from 3p which is better shielded than 3s
• WHY DOES THE IONISATION ENERGY OF S DEVIATE FROM THE GENERAL TREND?

  • e- is removed from 3p electron pair
  • repulsion between e- in pair
• WHAT IS THE MEANING OF FIRST IONISATION OF AN ATOM?

  energy required when electron is removed to form uni-positive ion from a gaseous atom
• WHY IS THE FIRST IONISATION ENERGY OF NEON HIGHER THAN SODIUM?

  • electron removed from shell of lower energy
  • 2p rather than 3s
  • less shielding