Question

The simplest hydrogen compound of phosphorus is phosphine, a highly flammable and poisonous compound with an odor of decaying fish. What is the formula for phosphine?

Short answer

The formula for phosphine is PH3.

Step-by-step solution

Identify the elements

The problem states that phosphine is a hydrogen compound of phosphorus. The two elements involved are phosphorus (P) and hydrogen (H).

Determine the simplest compound formula

The simplest hydrogen compound of an element typically involves a single atom of that element with the smallest number of hydrogen atoms needed to form a stable molecule. Phosphorus in its simplest hydride form is combined with three hydrogen atoms.

Write the chemical formula

Considering that phosphorus can form three bonds and hydrogen forms one, the formula for phosphine will be PH3, where P is for phosphorus and H is for hydrogen.

Key concepts

Phosphorus Compounds

Phosphorus is a versatile element and forms various compounds that are essential for life on Earth. In its pure form, phosphorus exists in several allotropes; white, red, and black are the most common. White phosphorus, red phosphorus, and black phosphorus exhibit different physical properties but they share the ability to form numerous compounds, particularly with hydrogen and oxygen.

Phosphorus compounds include phosphates, used in fertilizers, and organophosphates, which serve as insecticides and nerve agents. Phosphine, another phosphorus compound, is a key example of a phosphorus-hydrogen bond. These compounds play a crucial role in various fields like agriculture, medicine, and industrial chemistry. Their chemistry is intriguing because phosphorus can exhibit a range of oxidation states, from -3 to +5, which determines the types of compounds it can form.

Chemical Formula Derivation

Understanding the chemical formula of a compound is a fundamental exercise in chemistry and it's essential for predicting the properties and behaviors of the substance. Deriving the chemical formula involves several key steps:

• Identify the elements present in the molecule.
• Determine the valency or combining power of each element.
• Combine the elements in such a way that their valencies are satisfied, resulting in a neutral molecule.

In the case of phosphine, the derivation utilizes the facts that phosphorus has a valency of three in this compound and hydrogen has a valency of one. To reach a stable electronic configuration, one atom of phosphorus will bond with three hydrogen atoms. Thus, the chemical formula derived is Phosphine (PH_3).

Hydrogen Compounds

Hydrogen compounds, also known as hydrides, are a vast and varied class of substances that hydrogen forms with other elements. These range from simple diatomic molecules like hydrogen chloride (HCl) to complex organic compounds and metals hydrides like sodium hydride (NaH).The simplest hydrogen compound of any element forms when hydrogen's singular valency fills the outermost electron shell of another element, achieving a stable octet or duet configuration. Hydrogen can bond with almost all other elements, giving rise to a plethora of compounds, each with unique properties. Phosphine is a simple hydride of phosphorus, notable for its role in industrial chemistry and potential for use as a semiconductor material.