Question

In your own words, define or explain the following terms or symbols: (a) formula unit; (b) \(\mathrm{P}_{4} ;\) (c) molecular compound; (d) binary compound; (e) hydrate.

Short answer

Here are the definitions: (a) A formula unit is the simplest ratio of ions in an ionic compound. (b) \(\mathrm{P}_{4}\) is molecule of four phosphorus atoms. (c) A molecular compound is composed of two or more nonmetals bonded by sharing electrons. (d) A binary compound is composed of only two types of atoms or elements. (e) A hydrate is a compound with water molecules bound to its atoms.

Step-by-step solution

Define 'formula unit'

A formula unit in chemistry refers to the simplest ratio of ions represented in an ionic compound. It shows the proportion of atoms within a compound but not the actual number of atoms in a molecule. On the basic level, it can be compared to a blueprint of a molecule which shows only the ratio of atoms and not their actual number.

Explain '\(\mathrm{P}_{4}\)'

In chemistry, \(\mathrm{P}_{4}\) refers to a molecule that contains four phosphorus atoms. Phosphorus naturally exists as \(\mathrm{P}_{4}\) molecules, also known as white phosphorus. It is the simplest form of phosphorous.

Define 'molecular compound'

A molecular compound is made up of two or more nonmetals, and these nonmetals bond together by sharing electrons. This type of bond is referred to as a covalent bond. The resulting compound usually has lower melting and boiling points than ionic compounds.

Define 'binary compound'

A binary compound is a chemical compound that is composed of only two different elements. This term is often used to refer to compounds that are composed of just two types of atoms or elements.

Define 'hydrate'

A hydrate is a compound that has water molecules bound to its atoms. The water is often referred to as 'water of hydration.' Not all hydrates have the same number of water molecules bound to their atoms.

Key concepts

Formula Unit

In chemistry, the term **formula unit** is crucial when studying ionic compounds. It represents the simplest ratio of the constituent ions that compose the compound. While the term **molecule** is used for covalent compounds to describe the smallest entity, **formula unit** aids in understanding ionic lattice structures where molecules do not exist.

- Remember: Ionic compounds, like salt (NaCl), do not form molecules but instead create vast networks or crystals. - **Formula unit** acts like a blueprint, indicating the simplest repeating portion of the crystal lattice. It doesn't signify a standalone molecule with discrete numbers of atoms, but rather the core ratio, such as 1 Na for every 1 Cl.

This concept helps chemists express chemical formulas and understand the proportions of various ions within a compound.

Molecular Compound

Molecular compounds are vital in the realm of chemistry, specifically among nonmetals. These are formed when nonmetals bond together through covalent bonds, where they share pairs of electrons. This sharing creates a stable electronic arrangement for each atom involved.

- Unlike ionic compounds, which are made from metals and nonmetals, molecular compounds generally consist solely of nonmetals. - They often have lower melting and boiling points compared to ionic compounds because their intermolecular forces are generally weaker than the ionic bonds. - Examples include water (H extsubscript{2}O) and carbon dioxide (CO extsubscript{2}), where distinct molecules exist, and physical properties can widely vary.

Molecular compounds form discrete molecules, leading to a diverse range of physical states and characteristics.

Binary Compound

The term **binary compound** denotes simplicity and diversity, referring to compounds made up of exactly two different elements. This category encompasses both ionic and covalent compounds.

- Common examples are sodium chloride (NaCl) and carbon monoxide (CO). - Binary compounds might consist of a metal and a nonmetal, forming ionic types, or two nonmetals, resulting in covalent compounds.

They follow specific naming conventions. For ionic compounds, the metal retains its name, while the nonmetal takes an -ide suffix, like chloride. For covalent compounds, prefixes often denote the number of atoms involved. Understanding binary compounds involves recognizing simplicity in composition and diversity in potential chemical behavior.

Hydrate

Hydrates are an intriguing class of compounds, notable for their unique structure: they include water molecules within their crystal framework. The water is known as "water of hydration."

- It's important to identify hydrates by the fixed number of water molecules attached to each formula unit. - Anhydrate refers to the dehydrated form of a hydrate, without the water molecules. - An example is copper(II) sulfate pentahydrate (CuSO extsubscript{4}·5H extsubscript{2}O), where five water molecules exist per formula unit.

Hydrates are fascinating because their properties can markedly change upon losing or gaining water, influencing things such as color or mass. Recognizing hydrates involves understanding the inherent water molecules and their impact on the compound's physical properties.