d and f BLOCK ELEMENTS

Why do the enthalpies of hydration for transition metal ions generally become less negative (or more positive) as the charge density decreases?

• Because water molecules are polar.
• Because smaller ions are more hydrated.
• Because ions with lower charge density interact less strongly with polar water molecules, resulting in less energy released during hydration.
• Because hydration is always exothermic.

Why do the third ionization enthalpies of Cr and Cu have exceptionally high values?

• Because Cr and Cu are metals.
• Because Cr and Cu have high atomic numbers.
• Because removing the third electron disrupts the exceptionally stable half-filled (Cr: 3d^5) or fully-filled (Cu: 3d^10) 3d configurations.
• Because Cr and Cu are located at the end of the series.

Why do the atomic radii of transition metals not decrease as smoothly across the period compared to main group elements?

• Because transition metals are metals.
• Because d-electrons are added to the same shell.
• Because the nuclear charge decreases.
• Because the addition of d-electrons provides some shielding, partially counteracting the effect of increasing nuclear charge, leading to smaller, less regular decreases.

Why is the enthalpy of atomization generally lower for Zinc (Zn) compared to its neighbors like Iron (Fe) and Nickel (Ni)?

• Because Zinc has a lower melting point.
• Because Zinc is less dense.
• Because Zinc's metallic bonding primarily involves only 4s electrons, while its neighbors utilize both 4s and 3d electrons, leading to weaker overall bonding for Zn.
• Because Zinc is further to the right in the series.

Why does the second ionization enthalpy of transition metals not show the same large jump observed between the first and second IE of alkali metals?

• Because transition metals have higher atomic numbers.
• Because the first electron removed from transition metals is often from the ns orbital, and the second electron is removed from the (n-1)d orbital, which is not drastically different in energy.
• Because transition metals are less reactive.
• Because transition metals have more electrons.