Transition Elements Quiz

Stability of Oxidation States

• Cr3+ is more stable than Cr2+ due to achieving a noble gas configuration.
• Cu2+ is more stable in solution than Cu+ due to high hydration enthalpy.

Oxidation States of Transition Metals

• Cu shows +1 oxidation state in the gaseous form due to a stable full-filled 3d10 configuration.
• Higher oxidation states of transition metals are found in their oxides and fluorides due to stabilization by highly electronegative elements like O and F.
• Higher oxidation states are more common in oxides than fluorides due to the formation of dπ-pπ bonds between metal and oxygen.

Oxidation States in First Series Transition Elements

• +2 oxidation state becomes more stable moving from left to right as the number of unpaired electrons decreases.
• MnO4-, Cr2O7 2-, VO3 -, CrO4 2- are oxoanions of first series transition metals where the group number and oxidation number of the transition metal are the same.

Electrode Potential

• E0 for M2+/M becomes less negative moving from left to right, but shows an irregular trend due to irregular variation of IE1 + IE2.
• E0 Cu2+/Cu is +ve (+0.34 V) due to low hydration enthalpy of Cu2+.
• E0 Mn3+/Mn2+ is +ve because Mn2+ achieves a half-filled configuration.
• E0 Cr3+/Cr2+ is -ve because Cr3+ is more stable due to a half-filled t2g configuration.

Colour and Magnetism

• Most compounds of transition metals are coloured in solid and solution forms due to d-d transition.
• Sc3+, Ti4+ do not exhibit colour due to d0 configuration.
• Zn2+, Cu+ do not exhibit colour due to full-filled d10 configuration.
• Transition metals or ions are paramagnetic in nature due to the presence of unpaired electrons (d1-9).

Coordination Complexes

• Transition metals form a large number of coordination complexes due to high charge by mass ratio, availability of vacant d-orbitals, and variable oxidation states.

Interstitial Compounds

• Interstitial compounds are formed when small elements like H, B, C, N are trapped in the interstitial space of a metal lattice.
• Transition metals form interstitial compounds due to the availability of interstitial space in the metal lattice.
• Interstitial compounds are more useful than pure metals due to their high melting points and other useful properties.

Definition and Characteristics of Transition Metals

• d-block elements are called transition elements because they have incomplete d-orbitals in the neutral or most stable oxidation state.
• Zn, Hg, Cd are not included as transition elements because they have filled d-orbitals in the neutral and most stable +2 oxidation state.
• Sc3+ has a d0 configuration but is considered a transition metal due to its partially filled d1 configuration.
• First series transition elements show an irregular trend of atomic radii due to the shielding effect of inner 3d electrons.
• Atomic radii of Zr to Hf are almost the same due to lanthanoid contraction.
• First series transition elements show an irregular trend of IE due to the mutual exchange of energy between d and f orbitals.
• Transition metals have strong metallic bonds, high enthalpy of atomization, and high melting points due to the presence of unpaired electrons.
• Zn, Cd, Hg are not very hard and have low melting points and boiling points due to the presence of all paired electrons.
• d-block elements show a large number of oxidation states due to the presence of unpaired electrons or partially filled d-orbitals.
• Mn shows the highest number of oxidation states due to the presence of the highest number of unpaired electrons.
• Sc is the only first series transition metal that does not show variable oxidation states.