5.3.1 Transition Elements

• What are transition elements ?

  d-block elements that form one or more stable ions with partially filled d orbitals
• which elements are in the d block but are not transition elements ?

  scandium and zinc
• why are Sc and Zn not transition elements despite being in the d- block ?

  Scandium only forms Sc3+ ions which have an empty d subshell

  Zinc only forms Zn2+ ions which have a full d subshell
• what d block elements don't follow the electron configuration rule ?

  chromium and copper
• What is the electron configuration of chromium ?

  [Ar] 3d5 4s1
• What is the electron configuration of copper ?

  [Ar] 3d10 4s1
• why does chromium and coppers electron configuration not fit the rule ?

  chromium - a half filled d subshell provides greater stability

  copper - a full d subshell provides greater stability
• when transitions metal atoms form positive ions, the 4s electrons are removed first followed by the 3d electrons
• what are the 4 chemical properties of transition elements ?

  • existing in variable oxidative states
  • acting as catalysts
  • forming coloured ions
  • forming complex ions
• why do transition elements show variable oxidation states ?

  the 4s and 3d subshells have very similar energies so only a small amount of energy are needed to remove differing numbers of electrons to form stable ions in different oxidation states