lanthanoids are more paramagnetic than transition elements explain?
Answers
The Lanthanides consist of the elements in the f-block of period six in the periodic table. While these metals can be considered transition metals, they have properties that set them apart from the rest of the elements.
Introduction
The Lanthanides were first discovered in 1787 when a unusual black mineral was found in Ytterby, Sweden. This mineral, now known as Gadolinite, was later separated into the various Lanthanide elements. In 1794, Professor Gadolin obtained yttria, an impure form of yttrium oxide, from the mineral. In 1803, Berzelius and Klaproth secluded the first Cerium compound. Later, Moseley used an x-ray spectra of the elements to prove that there were fourteen elements between Lanthanum and Hafnium. The rest of the elements were later separated from the same mineral. These elements were first classified as ‘rare earth’ due to the fact that obtained by reasonably rare minerals. However, this is can be misleading since the Lanthanide elements have a practically unlimited abundance. The term Lanthanides was adopted, originating from the first element of the series, Lanthanum.
Like any other series in the periodic table, such as the Alkali metals or the Halogens, the Lanthanides share many similar characteristics. These characteristics include the following:
Similarity in physical properties throughout the series
Adoption mainly of the +3 oxidation state. Usually found in crystalline compounds)
They can also have an oxidation state of +2 or +4, though some lanthanides are most stable in the +3 oxidation state.
Adoption of coordination numbers greater than 6 (usually 8-9) in compounds
Tendency to decreasing coordination number across the series
A preference for more electronegative elements (such as O or F) binding
Very small crystal-field effects
Little dependence on ligands
Ionic complexes undergo rapid ligand-exchange
Electron Configuration
Similarly, the Lanthanides have similarities in their electron configuration, which explains most of the physical similarities. These elements are different from the main group elements in the fact that they have electrons in the f orbital. After Lanthanum, the energy of the 4f sub-shell falls below that of the 5d sub-shell. This means that the electron start to fill the 4f sub-shell before the 5d sub-shell.
The electron configurations of these elements were primarily established through experiments. The technique used is based on the fact that each line in an emission spectrum reveals the energy change involved in the transition of an electron from one energy level to another. However, the problem with this technique with respect to the Lanthanide elements is the fact that the 4f and 5d sub-shells have very similar energy levels, which can make it hard to tell the difference between the two.
Another important feature of the Lanthanides is the Lanthanide Contraction, in which the 5s and 5p orbitals penetrate the 4f sub-shell. This means that the 4f orbital is not shielded from the increasing nuclear change, which causes the atomic radius of the atom to decrease that continues throughout the series.
Table 1: Electron Configurations of the Lanthanide Elements
La
5d16s2
5d16s2
Tb
4f85d16s2
4f9 6s2 or 4f85d16s2
Ce
4f15d16s2
4f15d16s2
Dy
4f95d16s2
4f10 6s2
Pr
4f25d16s2
4f3 6s2
Ho
4f105d16s2
4f11 6s2
Nd
4f35d16s2
4f4 6s2
Er
4f115d16s2
4f12 6s2
Pm
4f45d16s2
4f5 6s2
Tm
4f125d16s2
4f13 6s2
Sm
4f55d16s2
4f6 6s2
Yb
4f135d16s2
4f14 6s2
Eu
4f65d16s2
4f7 6s2
Lu
4f145d16s2
4f145d16s2
Gd
4f75d16s2
4f75d16s2
Properties and Chemical Reactions
One property of the Lanthanides that affect how they will react with other elements is called the basicity. Basicity is a measure of the ease at which an atom will lose electrons. In another words, it would be the lack of attraction that a cation has for electrons or anions. In simple terms, basicity refers to have much of a base a species is. For the Lanthanides, the basicity series is the following:
La3+ > Ce3+ > Pr3+ > Nd3+ > Pm3+ > Sm3+ > Eu3+ >
Answer:
The Lanthanides consist of the elements in the f-block of period six in the periodic table. While these metals can be considered transition metals, they have properties that set them apart from the rest of the elements.
Introduction
The Lanthanides were first discovered in 1787 when a unusual black mineral was found in Ytterby, Sweden. This mineral, now known as Gadolinite, was later separated into the various Lanthanide elements. In 1794, Professor Gadolin obtained yttria, an impure form of yttrium oxide, from the mineral. In 1803, Berzelius and Klaproth secluded the first Cerium compound. Later, Moseley used an x-ray spectra of the elements to prove that there were fourteen elements between Lanthanum and Hafnium. The rest of the elements were later separated from the same mineral. These elements were first classified as ‘rare earth’ due to the fact that obtained by reasonably rare minerals. However, this is can be misleading since the Lanthanide elements have a practically unlimited abundance. The term Lanthanides was adopted, originating from the first element of the series, Lanthanum.
Like any other series in the periodic table, such as the Alkali metals or the Halogens, the Lanthanides share many similar characteristics. These characteristics include the following:
Similarity in physical properties throughout the series
Adoption mainly of the +3 oxidation state. Usually found in crystalline compounds)
They can also have an oxidation state of +2 or +4, though some lanthanides are most stable in the +3 oxidation state.
Adoption of coordination numbers greater than 6 (usually 8-9) in compounds
Tendency to decreasing coordination number across the series
A preference for more electronegative elements (such as O or F) binding
Very small crystal-field effects
Little dependence on ligands
Ionic complexes undergo rapid ligand-exchange
Electron Configuration
Similarly, the Lanthanides have similarities in their electron configuration, which explains most of the physical similarities. These elements are different from the main group elements in the fact that they have electrons in the f orbital. After Lanthanum, the energy of the 4f sub-shell falls below that of the 5d sub-shell. This means that the electron start to fill the 4f sub-shell before the 5d sub-shell.
The electron configurations of these elements were primarily established through experiments. The technique used is based on the fact that each line in an emission spectrum reveals the energy change involved in the transition of an electron from one energy level to another. However, the problem with this technique with respect to the Lanthanide elements is the fact that the 4f and 5d sub-shells have very similar energy levels, which can make it hard to tell the difference between the two.
Another important feature of the Lanthanides is the Lanthanide Contraction, in which the 5s and 5p orbitals penetrate the 4f sub-shell. This means that the 4f orbital is not shielded from the increasing nuclear change, which causes the atomic radius of the atom to decrease that continues throughout the series.
Table 1: Electron Configurations of the Lanthanide Elements
La
5d16s2
5d16s2
Tb
4f85d16s2
4f9 6s2 or 4f85d16s2
Ce
4f15d16s2
4f15d16s2
Dy
4f95d16s2
4f10 6s2
Pr
4f25d16s2
4f3 6s2
Ho
4f105d16s2
4f11 6s2
Nd
4f35d16s2
4f4 6s2
Er
4f115d16s2
4f12 6s2
Pm
4f45d16s2
4f5 6s2
Tm
4f125d16s2
4f13 6s2
Sm
4f55d16s2
4f6 6s2
Yb
4f135d16s2
4f14 6s2
Eu
4f65d16s2
4f7 6s2
Lu
4f145d16s2
4f145d16s2
Gd
4f75d16s2
4f75d16s2
Properties and Chemical Reactions
One property of the Lanthanides that affect how they will react with other elements is called the basicity. Basicity is a measure of the ease at which an atom will lose electrons. In another words, it would be the lack of attraction that a cation has for electrons or anions. In simple terms, basicity refers to have much of a base a species is. For the Lanthanides, the basicity series is the following:
La3+ > Ce3+ > Pr3+ > Nd3+ > Pm3+ > Sm3+ > Eu3+ >