Which one of the following properties of white phosphorous are shared by red phosphorous? (a) It burns when heated in air (b) It dissolves in \(\mathrm{CS}_{2}\) (c) It phosphorescences in air (d) It reacts with \(\mathrm{NaOH}\) to give \(\mathrm{PH}_{3}\).

Phosphorous, a versatile and reactive nonmetal, exists in several forms, each with distinct chemical properties. Understanding these properties is crucial for comprehending how phosphorous behaves in different environments. For instance, phosphorous is characteristically a poor conductor of heat and electricity, and it reacts with various substances, including oxygen, halogens, and some metals. One notable chemical property is its high reactivity with oxygen; it easily forms phosphorus pentoxide when burned in air.

Additionally, an important reaction of phosphorous with bases such as sodium hydroxide (NaOH) highlights its chemical versatility. This particular reaction can yield several products, including phosphine (PH₃), depending on the conditions and the form of phosphorous used. Notably, both white and red phosphorus can react with NaOH to give PH₃, revealing a shared chemical property. Furthermore, in aqueous solutions, various oxidation states of phosphorous can be observed, showcasing its rich chemistry.

• High reactivity with oxygen
• Forms phosphine (PH₃) when reacted with sodium hydroxide (NaOH)
• Exhibits multiple oxidation states in aqueous solutions

When discussing the forms of phosphorous, most commonly, attention is drawn towards white and red phosphorous. These two forms are known as allotropes and showcase varied properties. White phosphorous is noted for its translucence and waxy appearance. It is highly reactive, even dangerous, as it can spontaneously ignite in air at temperatures around 30°C. Moreover, it is stored under water to prevent this reaction and dissolves in carbon disulfide (CS₂).

On the other hand, red phosphorous is more stable than its white counterpart. It does not spontaneously ignite in air and is less reactive. Red phosphorous does not glow in the dark, a property known as phosphorescence, which is exhibited by white phosphorous. It's these differences in reactivity and physical properties that make the handling of the two materials markedly different.

Safety and Reactivity

• White phosphorous is highly reactive and stored under water.
• Red phosphorous is stable and less reactive compared to white phosphorous.

Both white and red phosphorous can burn in air when heated, an attribute that showcases their exothermic reactions with oxygen. Additionally, both can react with NaOH to produce phosphine, indicating a shared chemical behavior in specific reactions.

Phosphorous exists in several allotropic forms, which are physical forms in which an element can exist due to different arrangements of atoms. The most common allotropes of phosphorous include white and red phosphorous, but there are also others like black and violet phosphorous. Allotropes can have different physical and chemical properties due to the variation in the structure of the molecules or crystal lattice.

White phosphorous consists of P₄ tetrahedra, an arrangement that contributes to its high reactivity and sensitivity to light and heat. Reactivity is a prime chemical property that differentiates white phosphorous from its other allotropic companions. Conversely, red phosphorous forms an amorphous network, which grants it greater stability and a higher ignition point than white phosphorous. These structural differences account for the variance in properties like reactivity, the conditions under which they phosphoresce, and their solubility in solvents such as CS₂.

Structure-Property Relationship

• White phosphorous features P₄ tetrahedra and high reactivity.
• Red phosphorous has an amorphous network contributing to its stability.