| Front | Back | | --- | --- | | Why is zinc ($Zn$) classified as a d-block element but NOT a transition element? |

Zinc has a completely filled d-sublevel ($3d^{10}$) in both its elemental state ($[Ar] 3d^{10} 4s^2$) and its only stable ion ($Zn^{2+}$, $[Ar] 3d^{10}$).
Transition elements must have an incomplete d-sublevel in their atom or in at least one stable ion.

| | What is the general electron configuration pattern for transition elements? | $$(n-1)d^{1-10}ns^{0-2}$$ where $n$ represents the principal quantum number of the outermost shell. | | State the electron configuration of a neutral copper ($Cu$) atom and explain why it is anomalous. |

Configuration: $[Ar] 3d^{10} 4s^1$
Reason: A completely filled d-sublevel ($3d^{10}$) is exceptionally stable, causing one electron to be promoted from the $4s$ orbital.

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Based on the electronic configurations shown, why does scandium ($Sc$) form a $Sc^{3+}$ ion that is colorless and diamagnetic?

$Sc^{3+}$ has the configuration $[Ar] 3d^0 4s^0$.
It has no d-electrons, meaning no $d$-$d$ transitions can occur (colorless) and there are no unpaired electrons (diamagnetic).

| | Why do transition metals exhibit variable oxidation states, whereas s-block metals (like sodium) do not? |

The energy difference between the $(n-1)d$ and $ns$ sublevels is very small.
This allows both $s$ and $d$ electrons to be lost with similar energy inputs.

| | What is the range of oxidation states exhibited by manganese ($Mn$)? | From +2 to +7. | | Why can manganese ($Mn$) reach a high oxidation state of +7? | It can lose or share all seven of its valence electrons (two $4s$ and five $3d$ electrons) due to the small energy difference between these sublevels. | | Explain how the color of transition metal complex ions arises. |

Ligands split the $d$-orbitals into two groups of different energy levels.
Electrons absorb a specific wavelength of visible light to transition from a lower to a higher $d$-orbital.
The complementary color of the absorbed wavelength is transmitted/observed.

| | Why are $Zn^{2+}$ compounds colorless in aqueous solution? |

$Zn^{2+}$ has a completely filled d-sublevel ($3d^{10}$).
There are no empty spaces in the upper $d$-orbitals to allow for $d$-$d$ electron transitions.

| | When a transition metal complex absorbs a specific wavelength of light to promote a $d$-electron, the compound displays the complementary color. | When a transition metal complex absorbs a specific wavelength of light to promote a $d$-electron, the compound displays the complementary color. | | Why do transition metals generally have much higher melting points than s-block metals? |

They have stronger metallic bonding.
Both $3d$ and $4s$ electrons are delocalized into the metallic lattice, increasing the electrostatic attraction.

| | Why are transition metals and their compounds highly effective catalysts? |

They can adopt variable oxidation states to form temporary intermediate complexes.
They provide a surface to adsorb reactant molecules, weakening their bonds.

| | In the Haber process for ammonia synthesis, iron acts as the catalyst. | In the Haber process for ammonia synthesis, iron acts as the catalyst. | | In catalytic converters, platinum is used to facilitate the oxidation of carbon monoxide to carbon dioxide. | In catalytic converters, platinum is used to facilitate the oxidation of carbon monoxide to carbon dioxide. | | What causes paramagnetism in transition metal complexes? | The presence of unpaired electrons in the $d$-sublevel, which creates a weak attraction to an external magnetic field. | | What causes diamagnetism in a d-block species like $Zn^{2+}$? | All electrons are paired, which causes a weak repulsion from an external magnetic field. | | What is ferromagnetism and how does it differ from paramagnetism? |

Ferromagnetism is a strong, permanent magnetic alignment of unpaired electron spins.
Unlike paramagnetism, the magnetic alignment remains even when the external magnetic field is removed.

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Based on the table, why does $Mn^{4+}$ show a stronger paramagnetic response than $Cu^{2+}$?

$Mn^{4+}$ has three unpaired electrons, whereas $Cu^{2+}$ has only one unpaired electron.
A higher number of unpaired electrons increases the strength of the paramagnetic attraction.

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Looking at this section of the periodic table, which group number contains elements that are in the d-block but are NOT considered transition elements?

| Group 12 (containing zinc, cadmium, and mercury), because they do not form any stable ions with an incomplete d-sublevel. | | The splitting of the $d$-orbitals into two distinct energy levels occurs in the presence of ligands. | The splitting of the $d$-orbitals into two distinct energy levels occurs in the presence of ligands. | |

| Weak effect | |

| Ni2+ | |

| 3d | |

| Ion | |

| Zn2+ | |

| No effect* |

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry S3.1.8 Properties of Transition Elements Flashcards

Flashcards for S3.1.8 Properties of transition elements (HL only)