transition metals

• What are transition metals defined as in the periodic table?

  Elements in the d-block that form one or more stable ions with a partially filled d-orbital
• How do transition metals typically lose electrons to form positive ions?

  They lose electrons from the s-orbital first
• What are the common physical properties of transition metals?

  • Similar atomic radius
  • High densities
  • High melting points
  • High boiling points
• What are the special chemical properties of transition metals?

  • They form complexes
  • They form coloured ions in solution
  • They have variable oxidation states
  • They act as good catalysts
• Why do transition metals have variable oxidation states?

  Because the 4s and 3d orbitals are very close in energy levels
• What is the electron configuration of Scandium (atomic number 21)?

  [Ar] 4s$^2$ 3d$^1$
• What is the electron configuration of Nickel (atomic number 28)?

  [Ar] 4s$^2$ 3d$^7$
• What is the electron configuration of Iron (atomic number 26)?

  [Ar] 4s$^2$ 3d$^6$
• What is the electron configuration of Fe$^{2+}$?


  [Ar] 4s$^0$ 3d$^6$ or [Ar] 3d$^6$
• What is the electron configuration of Vanadium (atomic number 23)?

  [Ar] 4s$^2$ 3d$^3$
• What is the electron configuration of V$^{2+}$?


  [Ar] 4s$^0$ 3d$^3$ or [Ar] 3d$^3$
• What are the exceptions to the electron configuration rule for transition metals?

  • Copper and chromium are exceptions.
  • Chromium: [Ar] 4s$^1$ 3d$^5$ instead of [Ar] 4s$^2$ 3d$^4$.
  • Copper: [Ar] 4s$^1$ 3d$^10$ instead of [Ar] 4s$^2$ 3d$^9$.
• What is a complex in transition metal chemistry?

  • A complex consists of a central metal ion surrounded by ligands.
  • Ligands are molecules or ions that donate electron pairs to the metal ion.

  
• What is a ligand?

  A molecule or ion with a lone electron pair that forms a dative bond to the central metal ion
• What are the types of ligands based on the number of coordinate bonds they form?

  • Monodentate: form one coordinate bond (e.g., H₂O, Cl^-, NH₃)
  • Bidentate: form two coordinate bonds (e.g., NH₂CH₂CH₂NH₂)
  • Hexadentate: form six coordinate bonds (e.g., EDTA^4-)
  • Polydentate/multidentate: form more than one coordinate bond
• What is the coordination number of a transition metal complex?

  The total number of coordinate bonds formed with the central metal ion
• What is the coordination number of silver complexes?

  2
• What is the coordination number of platinum complexes?

  4
• How can transition metal ions be identified?

  By their colour, which changes depending on coordination number, ligand type, and oxidation state
• How does colour arise in transition metal ions?

  • Colour arises from the absorption and reflection of light.
  • Some wavelengths are absorbed while others are reflected and transmitted to the human eye.
• What happens to the d-orbital in transition metal complexes when ligands are present?

  The d-orbital splits, causing some electrons to exist in a higher energy level
• What does the change in energy (∆E) between d-orbital states correspond to?

  It corresponds to a specific wavelength and frequency of light
• Why are some metal ions and complexes colourless?

  Because they have no available electrons to excite and move around
• Why is zinc considered colourless in transition metal chemistry?

  Because it has completely filled d-orbitals
• What are the shapes of transition metal complexes?

  • Octahedral: bond angle of 90° with six-fold coordination (e.g., H₂O, NH₃)
  • Tetrahedral: bond angle of 109.5° with larger ligands (e.g., Cl^-)
  • Square planar: bond angle of 90° (e.g., platinum and nickel complexes)
• What is the significance of cisplatin in medicine?

  Cisplatin is used as a cancer therapy drug
• What are the side effects of cisplatin?


  It can cause serious side effects such as hair loss
• What occurs during ligand substitution in transition metal complexes?

  Ligands can be exchanged for other ligands
• What is haem and its role in the body?

  • Haem is a common multidentate ligand.
  • It consists of six coordinate bonds around a central Fe$^{2+}$ ion.
  • It transports oxygen around the body.
• What happens when carbon monoxide binds to haem?

  It replaces the oxygen bound to haem, making it toxic
• What are the oxidation states of vanadium?

  +5, +4, +3, +2
• How does vanadium produce different coloured compounds?

  • Each oxidation state produces a different coloured compound.
  • The colours can be remembered by the phrase: "You Better Get Vanadium."
• What is the role of zinc in the reduction of vanadium?

  Zinc reduces vanadium from +5 to +2 in acidic solution
• What do the E$_{cell}$ values indicate about the reduction of vanadium?


  Reduction becomes less favourable as the oxidation state of vanadium decreases
• How does pH affect the oxidation state of transition metals?

  Acidic conditions are required for reduction, while alkaline conditions are needed for oxidation
• What are the most stable oxidation states of chromium?

  +6, +3, +2
• How can Cr$_{2}O_{7}^{2-}$ be reduced?


  By reduction with zinc in acidic conditions
• How can Cr$^{3+}$ be oxidized?


  By hydrogen peroxide in alkaline conditions
• What is the equilibrium reaction involving CrO$_{4}^{2-}$ and Cr$_{2}O_{7}^{2-}$?


  • 2CrO$_{4}^{2-}$ + 2H$^{+}$ ⇌ Cr$_{2}O_{7}^{2-}$ + H$_{2}O$
  • Acidification shifts the equilibrium to the right, increasing Cr$_{2}O_{7}^{2-}$ concentration.
• What happens to metal ions in water?

  They become hydrated, forming H₂O ligands around the central metal ion