Difference Between Transition Metals and Inner Transition Metals

Main Difference – Transition Metals vs Inner Transition Metals

The periodic table of elements is composed of metals, nonmetals, and metalloids. Chemical elements are categorized as metals if they have metallic properties such as malleability, good electrical conductivity, easily remove electrons, etc. Transition metals and inner transition metals are also metallic elements that are categorized as such, considering their electron configurations. Most d block elements are considered as transition metals. F block elements are considered as inner transition metals. The main difference between transition metals and inner transition metals is that transition metal atoms have their valence electrons in the outermost d orbital whereas inner transition metal atoms have their valence electrons in the f orbital of the inner penultimate electron shell.

Key Areas Covered

1. What are Transition Metals
      – Definition, Properties in Relation to Electronic Configuration
2. What are Inner Transition Metals
      – Definition, Properties in Relation to Electronic Configuration
3. What is the Difference Between Transition Metals and Inner Transition Metals
      – Comparison of Key Differences

Key Terms: Actinides, D Orbital, F Orbital, Inner Transition Metal, Lanthanides, Transition Metal

What are Transition Metals

Transition metals are chemical elements that are composed of atoms with unpaired d electrons; even the stable cations these elements make have unpaired d electrons. Most d block elements are transition metals. However, Scandium (Sc) and Zinc (Zn) are not considered as transition metals since they have no unpaired d electrons, even in the stable cations they form. Scandium forms Sc⁺³ as the only stable cation and it has no d electrons. Zn forms Zn⁺² cation as the only stable cation. It has d electrons, but all of them are paired.

In the periodic table of elements, all transition metals are found among the d block elements. These d block elements are located between the s block elements and the p block elements. S block elements are metals. P block elements are nonmetals. Therefore, d block elements show the transition of metals to nonmetals and are called transition metals.

Transition metals can form different compounds in different oxidation states. All the cations formed by transition metals are colorful. Therefore, the compounds made by those metals are also very colorful. The compounds formed by the same transition metal element are found in different colors. This is because the different oxidation states of the same element show different colors.

Figure 1: Colors of Different Nickel Complexes

Transition metals can form complex compounds. They are called coordination compounds. The transition metal atom is centered by several ligands that donate their lone electron pairs to the central metals atom.

What are Inner Transition Metals

Inner transition metals are chemical elements that are composed of valence electrons in their f orbitals of the penultimate electron shell. F block elements are known as inner transition metals since they are composed of valence electrons in their f orbitals and those f orbitals are surrounded by other atomic orbitals.

Lanthanide series and actinide series are the two periods of the f block. Lanthanide series is composed of chemical elements that have valence electrons in their 4f orbital. Actinide series is composed of chemical elements that have their valence electrons in the 5f orbital.

Figure 2: Blocks in the Periodic Table

Inner transition metals are composed of very large atoms since they have a high number of shells. Therefore, most of them are unstable and radioactive. Almost all actinides are radioactive elements, but lanthanides are non-radioactive with some exceptions.

The most prominent oxidation state of inner transition metals is +3. But actinides can have up to +6 oxidation state. Inner transition metals show atomic numbers ranging from 57 to 103.

Difference Between Transition Metals and Inner Transition Metals

Definition

Transition Metals: Transition metals are chemical elements that are composed of atoms having unpaired d electrons, even their stable cations have unpaired d electrons.

Inner Transition Metals: Inner transition metals are chemical elements that have valence electrons in their f orbitals of the penultimate electron shell.

Location in the Periodic Table

Transition Metals: Transition metals are in the d block of the periodic table.

Inner Transition Metals: Inner transition metals are in the f block of the periodic table.

Atomic Numbers

Transition Metals: Transition metals have atomic numbers ranging from 21 to 112.

Inner Transition Metals: Inner transition metals have atomic numbers ranging from 57 to 103.

Abundance

Transition Metals: Transition metals are abundant on earth.

Inner Transition Metals: Inner transition metals are less abundant on earth.

Most Prominent Oxidation State

Transition Metals: The most prominent oxidation state of transition metals is +2.

Inner Transition Metals: The most prominent oxidation state of inner transition metals is +3.

Conclusion

Transition metals and inner transition metals are chemical elements that have a higher atomic number and large atomic sizes. Therefore, most of them are considered as heavy metals. The main difference between transition metals and inner transition metals is that transition metal atoms have their valence electrons in the outermost d orbital whereas inner transition metal atoms have their valence electrons in the f orbital of the inner penultimate electron shell.

References:

1. “Transition Elements.” Transition Elements, Inner Transition Elements | [email protected], Available here. Accessed 8 Sept. 2017.
2. “Transition Metals.” Bonder Research Web, chemed. Available here. Accessed 8 Sept. 2017.

Image Courtesy:

1. “Color of various Ni(II) complexes in aqueous solution” By LHcheM – Own work (CC BY-SA 3.0) via Commons Wikimedia 
2. “Periodic Table structure” By Sch0013r – File:PTable structure.png (CC BY-SA 3.0) via Commons Wikimedia