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D-Block Elements Periodic Table

The d-block elements are elements in groups 3 through 12 in which the highest electron energy subshell is a d-subshell. Their general electron configuration is [Noblegas](n−1)d1−10ns0−2. The “d” stands for “diffuse” and the azimuthal quantum number is 2. You’ll often hear the d-block elements called the transition metals, and this is mostly true. Here’s a closer look at which elements are d-block elements, their properties, and how they compare with the transition metals.

Locating D-Block Elements on the Periodic Table

The d-block spans groups 3 to 12 across four periods (4, 5, 6, and 7). These elements fit between the s-block and p-block elements, encompassing the metals from scandium to zinc, yttrium to cadmium, hafnium to mercury, and rutherfordium to copernicium.

Some chemists include lanthanum and actinium. Some include lutetium and lawrencium.

Table of D-Block Elements

Group3456789101112
Period 421Sc22Ti23V24Cr25Mn26Fe27Co28Ni29Cu30Zn
539Y40Zr41Nb42Mo43Tc44Ru45Rh46Pd47Ag48Cd
671Lu72Hf73Ta74W75Re76Os77Ir78Pt79Au80Hg
7103Lr104Rf105Db106Sg107Bh108Hs109Mt110Ds111Rg112Cn

D-Block Elements vs Transition Metals

Although often used interchangeably, “d-block elements” and “transition metals” are not exactly synonymous. The IUPAC defines a transition metal as an element with atoms that have an incomplete d-subshell. In contrast, a d-block element is one where the highest energy subshell is the d-subshell. So, if you adhere to strict definitions, the two groups overlap, but are not identical. (Also, note that these definitions are not agreed upon by all chemists.)

For example, the transition metals group sometimes excludes zinc, cadmium, and mercury because they each have a complete d shell.

Lanthanum, Actinium, Lutetium, and Lawrencium

Are lanthanum, actinium, lutetium, and lawrencium d-block elements? Are they transition metals? Chemists disagree on the answers.

Lanthanum ([Xe]5d16s2) and actinium ([Rn]6d17s2) each have one electron in the d-subshell and none in the f-subshell. Yet, their chemical behavior aligns with the lanthanides and actinides, as they set the stage for filling the f-orbital. Ultimately, the classification of lanthanum and actinium as f-block elements primarily reflects their chemical behavior and historical placement in the periodic table rather than strictly following the electron configuration that might suggest a d-block categorization.

Similarly, lutetium ([Xe]4f145d16s2) and lawrencium (either [Rn]5f147s27p1 or [Rn]5f147s26d1) have a partially filled d-shell (at least for lutetium) and potentially qualify as transition metals and d-block elements. However, they have f-subshell electrons. In lutetium, the f-shell is filled, so the element behaves much like any other group 3 d-block element. Lawrencium is a bit tricky because its electron configuration is unclear.

Properties of the D-Block Elements

The d-block elements typically exhibit these common properties (with exceptions):

  • High melting and boiling points
  • Good conductors of heat and electricity
  • Variable oxidation states
  • Formation of colored compounds
  • Catalytic properties

These properties arise from the complex electronic configurations and the availability of d-electrons for bonding.

High Melting and Boiling Points

These elements have high melting and boiling points because they have multiple electrons in their d-orbitals which participate in metallic bonding. So, they form stronger bonds between atoms that require higher energy to break.

Excellent Conductors

Their high conductivity results from the easily delocalized d-electrons that move through the metallic lattice. Also, the overlap of d-orbitals serves as a pathway for electron movement, facilitating the flow of heat and electricity.

Variable Oxidation States

Incompletely filled d-orbitals help atoms readily gain or lose electrons, giving them multiple oxidation states. Also, the energy difference between the s- and d-orbitals is relatively small. Promoting or removing electrons from these orbitals is pretty easy.

Colored Compounds

The presence of partially filled d-orbitals allows for the absorption of visible light, which leads to electronic transitions within the d-orbitals themselves (d-d transitions). When light gets absorbed, the remaining transmitted or reflected light exhibits color. In compounds, the arrangement of ligands around the central metal atom can cause a splitting of the d-orbital energy levels.

Crystal field splitting also plays a role. In compounds, the arrangement of ligands around the central metal atom sometimes causes a splitting of the d-orbital energy levels. Different ligands and geometries lead to different energy gaps, thus absorbing different wavelengths of light and resulting in various colors.

Catalytic Properties

The d-block elements participate in a variety of chemical reactions because of how easily they switch between oxidation states and their available empty d-orbitals. As metals, their surfaces promote chemical reactions. Surface sites weaken bonds in reactants, adjust the arrangement of electrons, and lower activation energies.

Magnetism in D-Block Elements

The magnetic properties of d-block elements vary widely, mainly depending on the presence of unpaired electrons in the d-orbitals. The crystal and electronic structure also play roles.

  • Paramagnetism
    • Definition: This occurs when a material is only magnetic in the presence of an external magnetic field.
    • Mechanism: Paramagnetism in d-block elements results from the presence of unpaired d-electrons. These unpaired electrons have magnetic moments that align with an external magnetic field, making the material magnetic.
    • Example: Titanium (Ti) and copper (Cu) exhibit paramagnetism due to their unpaired electrons.
  • Diamagnetism
    • Definition: Diamagnetism is a form of magnetism that occurs in materials that have no unpaired electrons. These materials create an induced magnetic field in a direction opposite to that of the applied magnetic field, resulting in a repulsive effect.
    • Mechanism: In d-block elements, diamagnetism occurs when all the electrons are paired. Paired electrons cancel out each other’s magnetic moments.
    • Example: Zinc (Zn) is a good example of a diamagnetic d-block element that has a completely filled d-subshell.
  • Ferromagnetism
    • Definition: Ferromagnetism is the strongest form of magnetism. It occurs in materials that not only have unpaired electrons but also have domains where these electrons’ spins align in the same direction even without an external magnetic field.
    • Mechanism: This type of magnetism is rare in pure d-block elements but occurs in some alloys and compounds involving d-block elements where the exchange interactions between unpaired electrons in different atoms are strong enough to align their spins.
    • Example: Iron (Fe), cobalt (Co), and nickel (Ni) are classic examples of ferromagnetic materials.

Complex magnetic behavior also occurs. For example, manganese (Mn) exhibits several oxidation states, each with a different number of unpaired electrons. Mn in its elemental form is paramagnetic, but it forms compounds that are diamagnetic or even antiferromagnetic.

References

  • IUPAC (2006). “Transition element.” IUPAC Compendium of Chemical Terminology (3rd ed.). doi:10.1351/goldbook.T06456
  • Jensen, William B. (2015). “The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table: an update”. Foundations of Chemistry. 17: 23–31. doi:10.1007/s10698-015-9216-1
  • Petrucci, Ralph H.; Harwood, William S.; Herring, F. Geoffrey (2002). General Chemistry: Principles and Modern Applications (8th ed.). Upper Saddle River, N.J: Prentice Hall. ISBN 978-0-13-014329-7.
  • Scerri, Eric (2020). “Recent attempts to change the periodic table”. Philosophical Transactions of the Royal Society A. 378 (2180). doi:10.1098/rsta.2019.0300
  • Thyssen, P.; Binnemans, K. (2011). “Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis”. In Gschneidner, K. A. Jr.; Bünzli, J-C.G; Vecharsky, Bünzli (eds.). Handbook on the Physics and Chemistry of Rare Earths. Vol. 41. Amsterdam: Elsevier. pp. 1–94. doi:10.1016/B978-0-444-53590-0.00001-7