Question

The most stable oxidation state of titanium is

• A. \(\text{Ti}^{3+}\)
• B. \(\text{Ti}^{2+}\)
• C. \(\text{Ti}^{4+}\)
• D. \(\text{Ti}^{5+}\)

Hint:

Remember the most stable states of early 3d metals:
\(\text{Sc}^{3+}\) (\(d^0\)), \(\text{Ti}^{4+}\) (\(d^0\)), and \(\text{V}^{5+}\) (\(d^0\)) are the most stable because they achieve the inert argon configuration.

Answer 1

The Correct Option is C

Concept:
The relative stability of transition metal oxidation states is closely related to the electronic configuration of the resulting cation.
Configurations with completely empty (\(d^0\)), half-filled (\(d^5\)), or fully filled (\(d^{10}\)) subshells possess extra stability.

Step 1: Electronic Configuration of Titanium:
Titanium is the second element of the 3d-transition series, with atomic number \(Z = 22\).
Its ground-state electronic configuration is:
\[ \text{Ti} \, (Z = 22): [\text{Ar}] \, 3d^2 4s^2 \] It has four valence electrons available for chemical bonding.

Step 2: Assessing Available Oxidation States:
Titanium commonly displays \(+2\), \(+3\), and \(+4\) oxidation states:
- In \(\text{Ti}^{2+}\), the configuration is \([\text{Ar}] \, 3d^2\). These ions are strong reducing agents and easily oxidize to higher states.
- In \(\text{Ti}^{3+}\), the configuration is \([\text{Ar}] \, 3d^1\). These ions are reducing and tend to undergo oxidation to the \(+4\) state.
- In \(\text{Ti}^{4+}\), all four valence electrons (two from \(4s\) and two from \(3d\)) are removed:
\[ \text{Ti}^{4+}: [\text{Ar}] \, 3d^0 4s^0 \] In the \(+4\) state, titanium acquires the stable noble gas electronic configuration of argon (\([\text{Ar}]\)).

Step 3: Feasibility of the \(+5\) State:
The \(+5\) oxidation state does not exist under standard chemical conditions because removing a fifth electron requires breaking into the filled core of the noble gas argon shell, which requires very high ionization energy.
Hence, \(\text{Ti}^{4+}\) is the most stable and predominant oxidation state of titanium.
Final Answer:
The most stable oxidation state of titanium is \(\text{Ti}^{4+}\), corresponding to option (C).