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Red phosphorus is less reactive than white phosphorus due to differences in their molecular structures and arrangements of atoms. White phosphorus consists of tetrahedral P4 molecules, each containing four phosphorus atoms bonded together in a highly strained, reactive structure. These P4 molecules are held together by weak van der Waals forces.

In contrast, red phosphorus has a polymeric structure, with long chains or layers of phosphorus atoms bonded together in a more stable arrangement. This structure makes it less prone to spontaneous combustion and less reactive with other substances compared to white phosphorus.

Additionally, white phosphorus is highly reactive because it readily reacts with oxygen in the air to form phosphorus pentoxide, producing intense heat and light, which can lead to spontaneous ignition. Red phosphorus, on the other hand, is much less reactive with oxygen and requires higher temperatures to ignite.

The "lanthanoid contraction" refers to a phenomenon observed in the periodic table involving the contraction in atomic and ionic radii as you move across the lanthanide series (also known as the rare earth elements) from left to right.

This contraction occurs due to the poor shielding effect of f-electrons in the lanthanoid series. As electrons are added to the f-orbitals, they are not very effective at shielding the increasing nuclear charge from the outermost s- and p-electrons. As a result, the effective nuclear charge experienced by the outer electrons increases, leading to a contraction in the size of the atoms and ions as you move across the lanthanide series.

The lanthanoid contraction has significant consequences in various chemical properties, including ionization energy, atomic and ionic radii, and complex formation.

Transition elements exhibit variable oxidation states due to the presence of incompletely filled d orbitals in their atoms. These d orbitals can participate in bonding and can gain or lose electrons to form compounds with different oxidation states.

The number of oxidation states displayed by transition metals is often related to their electronic configurations. Transition metals have multiple incompletely filled d orbitals, which can easily lose or gain electrons to achieve a stable configuration. This flexibility allows them to exhibit a range of oxidation states.

For example, iron (Fe) can form compounds where it has an oxidation state of +2 or +3. In the +2 oxidation state, iron loses two electrons from its 4s orbital, while in the +3 oxidation state, it loses three electrons from both its 4s and 3d orbitals. Similarly, elements like chromium (Cr) can exhibit oxidation states ranging from -2 to +6.

The variability in oxidation states allows transition metals to form a wide variety of compounds with different properties and reactivities, making them essential in many chemical reactions and industrial processes.

The oxidation state of manganese (Mn) in its oxo-anion can be equal to its group number, which is +7. So, the formula of the oxo-anion would be MnO₄^(-), which is called permanganate ion.

Coordination isomerism occurs when both cation and anion in a complex ion are exchanged with each other. Here's an example:

Consider the coordination compounds [Co(NH₃)₅Cl]Cl₂ and [CoCl₅(NH₃)]²⁻.

In the first compound, [Co(NH₃)₅Cl]Cl₂, the cobalt ion is surrounded by five ammonia ligands and one chloride ion. The counter ion is another chloride ion.

In the second compound, [CoCl₅(NH₃)]²⁻, the cobalt ion is surrounded by five chloride ions and one ammonia ligand. The counter ion is a neutral ammonia molecule.

In both cases, the coordination sphere of cobalt is different, but the overall formula of the compounds remains the same. This is an example of coordination isomerism.

Sure! Ionization isomerism is a type of structural isomerism where the composition of ions within a complex compound changes.

An example of ionization isomerism is seen in the coordination compound [Co(NH3)5SO4]Br and [Co(NH3)5Br]SO4.

In the first compound, [Co(NH3)5SO4]Br, the sulfate ion (SO4) is coordinated to the cobalt ion (Co) while the bromide ion (Br) is outside the coordination sphere.

In the second compound, [Co(NH3)5Br]SO4, the bromide ion (Br) is coordinated to the cobalt ion (Co) while the sulfate ion (SO4) is outside the coordination sphere.

So, in these two compounds, the ions are arranged differently around the central cobalt ion, leading to ionization isomerism.

The complex Co(NH3)5(NO2)2 exhibits two types of isomerism:

1. Coordination Isomerism: Coordination isomers occur when the ligands in a complex exchange places with anionic or neutral ligands outside the coordination sphere. In this complex, NO2 and NO3 can interchange positions, leading to the formation of coordination isomers.

2. Ionization Isomerism: Ionization isomers arise when there's a difference in the location of a ligand within a complex or between an ion and a molecule. In this case, the NO3^- ions in the coordination sphere can exchange positions with the NO3^- ions outside the coordination sphere.