Difference Between D Block Elements and Transition Elements

Main Difference – D Block Elements vs Transition Elements

Most people often use the two terms, d block elements and transition elements, interchangeably. This is because they assume that all d block elements are transition elements since most d block elements are transition elements. However, not all d block elements are transition elements. The main difference between d block elements and transition elements is that d block elements have either completely or incompletely filled d orbitals whereas transition elements have incompletely filled d orbitals at least in one stable cation that they form.

Key Areas Covered

1. What are D Block Elements
      – Definition, Properties, Examples
2. What are Transition Elements
      – Definition, Properties, Examples
3. What is the Difference Between D Block Elements and Transition Elements
      – Comparison of Key Differences

Key Terms: Aufbau principle, d Block, Diamagnetic, Ferromagnetic, Metallic bonds, orbitals, Paramagnetic, Transition Elements

What are D Block Elements

D Block Elements are chemical elements having electrons filled to their d orbitals. The very first requirement for an element to be a d block element is the presence of d orbitals. Elements having at least one electron in their d orbitals are categorized as d block elements. The d-block of the periodic table is located between the s-block and the p-block.

One important fact about d block elements is that they have d orbitals that are partially or completely filled with electrons. According to Aufbau principle, electrons fill orbitals according to the ascending order of the energies of orbitals. In other words, electrons fill the ns orbital before filling the (n-1) d orbital. This is because the energy of ns orbital is lower than (n-1) d orbital. In elements of the first row of the periodic table, electrons first fill the 4s orbital before filling the 3d orbital.

Figure 1: The location of D block in the periodic table of elements

But there are some exceptions as well. Although the energy level is lower, sometimes electrons fill the orbitals with the most stable electron configuration. For example, ns¹nd¹⁰ configuration is more stable than ns²nd⁹. That is due to the stability of the complete filling of the d orbitals. Such two examples are shown below.

Chromium (Cr)  =       [Ar]3d⁵4s¹

Copper (Cu)       =       [Ar]3d¹⁰4s¹

Figure 2: Copper (Cu) has one electron in 4s orbital and 10 electrons in 3d orbital

All d block elements are metals. They show very high melting points and boiling points due to their strong metallic bonds. The decreasing of the atomic radii is slight compared to that of s and p block elements. Moreover, the densities are very high due to the metallic nature. Due to the presence of d electrons, d block elements show variable oxidation states.

What are Transition Elements

Transition elements are chemical elements that have incompletely filled d orbitals at least in one stable cation they form. Most transition elements have incomplete d orbitals in their atoms and most of them form cations having unpaired electrons in d orbitals. Few such examples are shown below.

Titanium (Ti)     =       [Ar]3d²4s²   =       Ti⁺²  =       [Ar]3d²4s⁰

Vanadium (V)   =       [Ar]3d³4s²    =       V⁺³   =       [Ar]3d²4s⁰

Iron (Fe)           =       [Ar]3d⁶4s²    =       Fe⁺²  =       [Ar]3d⁶4s⁰

Cobalt (Co)      =       [Ar]3d⁷4s²    =       Co⁺³  =       [Ar]3d⁶4s⁰

Copper (Cu)    =       [Ar]3d¹⁰4s¹   =       Cu⁺²  =       [Ar]3d⁹4s⁰

There are some d block elements that are not considered as transition elements. This is because they do not form cations having incomplete d orbitals. Sometimes, the normal atom may have unpaired d electrons but the only stable cation they form may not have incomplete d orbital filling (Ex: Scandium). Followings are examples.

Scandium (Sc)   =       [Ar]3d¹4s²        =       Sc⁺³   =    [Ar]3d⁰4s⁰

Zinc (Zn)            =       [Ar]3d¹⁰4s²      =       Zn⁺²   =     [Ar]3d¹⁰4s⁰

All transition elements are belong to the d block of the periodic table. Transition elements are metals and are solids at room temperature. Most of them form cations with variable oxidation states. The complexes that are formed by including transition metals are very colorful.

Figure 3: Colorful complexes formed by transition elements

These transition metals have catalytic properties. Therefore, they are used as catalysts in chemical reactions. Almost all transition elements are either paramagnetic or ferromagnetic due to the presence of high numbers of unpaired electrons.

Relationship Between D Block Elements and Transition Elements

• All transition elements are d block elements, but not all d block elements are transition elements.
• Almost all the transition elements are in the d block of the periodic table
• Both have very high melting points and high boiling points.
• Most D block elements and all transition elements are solids at room temperature. 

Difference Between D Block Elements and Transition Elements

Definition

D Block Elements: D block elements are chemical elements having electrons filling to their d orbitals.

Transition Elements: Transition elements are chemical elements that have incompletely filled d orbitals at least in one stable cation they form.

Cations

D Block Elements: D block elements may or may not have incompletely filled d orbitals in their cations.

Transition Elements: Transition elements essentially have incompletely filled d orbitals in their stable cations.

Colors

D Block Elements: D block elements may or may not form colorful complexes.

Transition Elements: Transition elements always form colorful complexes.

Magnetic Properties

D Block Elements: Some d block elements are diamagnetic whereas others are paramagnetic or ferromagnetic.

Transition Elements: All transition elements are either paramagnetic or ferromagnetic.

Physical Properties

D Block Elements: Some d block elements are not solids at room temperature (Mercury is a liquid) but other d block elements are solids at room temperature.

Transition Elements: All transition metals are solids at room temperature.

Conclusion

Although d block elements and transition elements are often considered to be the same, there is a difference between d block elements and transition elements. All transition elements are d block elements. But all d block elements are not transition elements. This is because all d block elements cannot form at least one stable cation having incomplete d orbital filling in order to become a transition metal.

References:

1.”D-Block Elements.” D-Block Elements, Properties of Transition Metals | [email protected]. N.p., n.d. Web. Available here. 20 July 2017. 
2. Helmenstine, Anne Marie. “Why Are Transition Metals Called Transition Metals?” ThoughtCo. N.p., n.d. Web. Available here. 20 July 2017. 
3.”Transition metal.” Transition metal – New World Encyclopedia. N.p., n.d. Web. Available here. 20 July 2017. 

Image Courtesy:

1.”Periodic Table 2″ By Roshan220195 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2.”Electron shell 029 Copper – no label” By [[commons:User crap]] (original work by commons:User:Greg Robson) – (CC BY-SA 2.0 uk) via Commons Wikimedia
3.”Coloured-transition-metal-solutions” De  Benjah-bmm27 assumed (based on copyright claims) (Dominio público) via Commons Wikimedia