For the Lanthanides, the basicity series is the following: In simple terms, basicity refers to have much of a base a species is. In another words, it would be the lack of attraction that a cation has for electrons or anions. Basicity is a measure of the ease at which an atom will lose electrons. One property of the Lanthanides that affect how they will react with other elements is called the basicity. Table 1: Electron Configurations of the Lanthanide Elements Symbol 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. 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.Īnother important feature of the Lanthanides is the Lanthanide Contraction, in which the 5s and 5p orbitals penetrate the 4f sub-shell. 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. The electron configurations of these elements were primarily established through experiments. This means that the electron start to fill the 4f sub-shell before the 5d sub-shell. After Lanthanum, the energy of the 4f sub-shell falls below that of the 5d sub-shell. These elements are different from the main group elements in the fact that they have electrons in the f orbital. Similarly, the Lanthanides have similarities in their electron configuration, which explains most of the physical similarities. Ionic complexes undergo rapid ligand-exchange.A preference for more electronegative elements (such as O or F) binding.Tendency to decreasing coordination number across the series.Adoption of coordination numbers greater than 6 (usually 8-9) in compounds.They can also have an oxidation state of +2 or +4, though some lanthanides are most stable in the +3 oxidation state.Adoption mainly of the +3 oxidation state.Similarity in physical properties throughout the series. These characteristics include the following: Like any other series in the periodic table, such as the Alkali metals or the Halogens, the Lanthanides share many similar characteristics. The term Lanthanides was adopted, originating from the first element of the series, Lanthanum. However, this is can be misleading since the Lanthanide elements have a practically unlimited abundance. These elements were first classified as ‘rare earth’ due to the fact that obtained by reasonably rare minerals. The rest of the elements were later separated from the same mineral. Later, Moseley used an x-ray spectra of the elements to prove that there were fourteen elements between Lanthanum and Hafnium. In 1803, Berzelius and Klaproth secluded the first Cerium compound. In 1794, Professor Gadolin obtained yttria, an impure form of yttrium oxide, from the mineral. This mineral, now known as Gadolinite, was later separated into the various Lanthanide elements. The Lanthanides were first discovered in 1787 when a unusual black mineral was found in Ytterby, Sweden. As chlorine can easily accept an electron as compared to phosphorus and sulphur, the chemical reactivity increases from phosphorus to chlorine.\) Chlorine (Cl) has 7 valence electrons and needs only one more electron to complete its octet. Sulphur (S) has 6 valence electrons and needs 2 more electrons to complete its octet. Phosphorus (P) has 5 valence electrons and needs 3 electrons to complete its octet. Moving further right in the period towards non-metals, the chemical reactivity again gradually increases. This is because the number of valence electrons increases, making it difficult to lose electrons. The chemical reactivity gradually decreases as we go to aluminium (Al) and silicon (Si). On moving from left to right in a period of the periodic table, the chemical reactivity of the elements first decreases and then increases.įor example, in the third period elements comprising of Na, Mg, Al, Si, P, S and Cl, sodium (Na) is very reactive as it has one valence electron, and can therefore, lose its electron easily.
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