Question

Write the formula for each of the following phosphorus-containing ions, including the overall charge of the ion. a. phosphide b. phosphate c. phosphite d. hydrogen phosphate

Short answer

a. Phosphide: \(P^{-3}\) b. Phosphate: \(PO_4^{-3}\) c. Phosphite: \(PO_3^{-3}\) d. Hydrogen Phosphate: \(HPO_4^{-2}\)

Step-by-step solution

a. Phosphide

Phosphide is an ion derived from phosphorus (P) with a charge of -3. Its formula is simply P^(-3).

b. Phosphate

A phosphate ion is derived from the phosphorus (P) atom surrounded by four oxygen (O) atoms in a tetrahedral arrangement. It has a charge of -3 and its formula is PO₄^(-3).

c. Phosphite

It is derived from the phosphorus (P) atom surrounded by three oxygen (O) atoms, where one oxygen atom has a double bond with phosphorus. It has an overall charge of -3. The formula for a phosphite ion is PO₃^(-3).

d. Hydrogen Phosphate

In a hydrogen phosphate ion, one hydrogen (H) atom is bonded to one of the oxygen atoms in a phosphate ion, resulting in an overall charge of -2. The formula for a hydrogen phosphate ion is HPO₄^(-2).

Key concepts

Chemical Formulas

The chemical formula of a substance is a way to represent the elements contained in it and their respective proportions. This symbolic notation is crucial for understanding the composition of molecules and compounds. It often looks like a series of letters and numbers, with letters representing elements and subscripts showing the number of atoms of each element in the molecule. For example, the chemical formula for water is \( H_2O \), indicating two hydrogen atoms bonded to one oxygen atom.

When it comes to phosphorus-containing ions, their chemical formulas become slightly more complex due to their polyatomic nature, which means they are composed of more than one atom. We have phosphide with the formula \( P^{3-} \), reflecting a single phosphorus atom carrying a 3- charge. Phosphate has the formula \( PO_4^{3-} \), consisting of one phosphorus atom surrounded by four oxygen atoms, and similarly, phosphite is represented by \( PO_3^{3-} \), with one less oxygen atom than phosphate. Lastly, hydrogen phosphate is denoted as \( HPO_4^{2-} \), illustrating the presence of a hydrogen atom in the composition.

Polyatomic Ions

Polyatomic ions are charged entities composed of two or more covalently bonded atoms. Unlike monoatomic ions, which consist of single atoms, polyatomic ions act as a single unit and cannot be divided into smaller charged particles without altering their chemical properties.

In phosphorus chemistry, we often encounter several polyatomic ions. For instance, the phosphate ion \( PO_4^{3-} \) is a common polyatomic ion with a tetrahedral shape, making it an integral part of many biological molecules like DNA and ATP. Phosphite \( PO_3^{3-} \) is another example, often involved in various chemical reactions and biological processes. These ions have distinct properties and can form various compounds, including salts and esters, by combining with appropriate counter-ions.

Ion Charge

The charge of an ion is a fundamental property indicating the electric charge that an ion carries. It is a result of the loss or gain of electrons, with the loss resulting in a positive charge (cation) and the gain in a negative charge (anion). The charge of an ion is crucial as it determines how ions interact with each other, forming ionic bonds to create compounds.

Phosphorus-containing ions such as phosphide \( P^{3-} \) have a 3- charge, which means they have gained three electrons compared to the neutral phosphorus atom. On the other hand, the hydrogen phosphate ion \( HPO_4^{2-} \) has a 2- charge because it has two more electrons than protons. Recognizing the charge on an ion is key to predicting the formulas of the compounds they will form and understanding their behavior in chemical reactions.