Question

Write the formula for each of the following compounds: a. sodium oxide b. sodium peroxide c. potassium cyanide d. copper(II) nitrate e. selenium tetrabromide f. iodous acid g. lead(IV) sulfide h. copper(1) chloride i. gallium arsenide j. cadmium selenide k. zinc sulfide 1\. nitrous acid m. diphosphorus pentoxide

Short answer

The chemical formulas for the given compounds are: a. Na₂O b. Na₂O₂ c. KCℓ d. Cu(NO₃)₂ e. SeBr₄ f. HIO₂ g. PbS₂ h. CuCl i. GaAs j. CdSe k. ZnS 1. HNO₂ m. P₂O₅

Step-by-step solution

Identify the elements and their charges

Sodium (Na) has a charge of +1 and Oxygen (O) has a charge of -2.

Balance the charges

Since the charges are not the same, we will need to balance them. We can do this by treating the magnitude of the charges as subscripts for the ions. Na(+1) and O(-2).

Write the formula

The formula for sodium oxide is: Na2O. #b. sodium peroxide#

Identify the elements and their charges

Sodium (Na) has a charge of +1, and the peroxide ion (O2) has a charge of -2.

Balance the charges

Since the charges are not the same, we will need to balance them. We can do this by treating the magnitude of the charges as subscripts for the ions. Na(+1) and O2(-2).

Write the formula

The formula for sodium peroxide is: Na2O2. Here are the remaining compounds: #c. potassium cyanide# KCℓ #d. copper(II) nitrate# Cu(NO₃)₂ #e. selenium tetrabromide# SeBr₄ #f. iodous acid# HIO₂ #g. lead(IV) sulfide# PbS₂ #h. copper(1) chloride# CuCl #i. gallium arsenide# GaAs #j. cadmium selenide# CdSe #k. zinc sulfide# ZnS #1. nitrous acid# HNO₂ #m. diphosphorus pentoxide# P₂O₅

Key concepts

Chemical Nomenclature

Understanding the language of chemistry is crucial for writing and communicating chemical formulas effectively. Chemical nomenclature is the systematic naming of chemical compounds based on their composition and structure. Conventions for naming inorganic compounds involve using prefixes for denoting the number of atoms and suffixes to indicate the type of compound, such as '-ide' for simple compounds, '-ate' and '-ite' for polyatomic ions with more or fewer oxygens, respectively.

One of the bases of chemical nomenclature is the use of Roman numerals in parentheses to show the oxidation state of elements with variable charges, such as copper(II) in copper(II) nitrate. When naming molecular compounds, prefixes like mono-, di-, tri-, tetra-, etc., are used to denote the number of atoms of each element, as seen in diphosphorus pentoxide. This systematic approach allows chemists to denote the specific compound they are referring to, ensuring clear communication within the scientific community.

Ionic Charges

Ionic charges are essential when it comes to writing chemical formulas for ionic compounds. An ion is an atom or a group of atoms with a net electric charge due to the loss or gain of one or more electrons. Metals tend to lose electrons and form positive ions (cations), while nonmetals typically gain electrons and become negative ions (anions).

The charge of an ion is usually represented by a superscript beside the chemical symbol, such as Na⁺ for a sodium cation or O^2- for an oxide anion. When combining ions to form neutral compounds, the total positive charge must balance the total negative charge. This is why in sodium oxide, Na₂O, two sodium ions with +1 charge each balance one oxide ion with a -2 charge. Grasping the concept of ionic charges can help students predict the resulting formula of an ionic compound and correctly understand their underlying structure.

Compound Naming

Naming chemical compounds correctly is a fundamental skill in chemistry that avoids confusion and ensures proper understanding of molecular structures. Compound naming follows specific rules depending on the type of compound. For ionic compounds, the name consists of the cation (positive ion) followed by the anion (negative ion). For instance, NaCl is named sodium chloride.

For a compound with a transition metal that can have multiple oxidation states, the oxidation state is indicated with Roman numerals, such as in copper(I) chloride (CuCl). Some compounds also have common names, such as potassium cyanide (KCN), which is known by its common name rather than its systematic name. Additionally, certain polyatomic ions have unique names, such as the cyanide ion in potassium cyanide. Students learning compound naming should focus on recognizing patterns and applying the correct rules to various types of compounds.

Molecular Compounds

Molecular compounds consist of molecules, which are groups of atoms bonded covalently. Understanding how to name and write formulas for molecular compounds involves knowing the prefixes for the number of atoms and the convention of using the least electronegative element first. The second element is named with the suffix '-ide,' such as in selenium tetrabromide (SeBr₄), denoting a molecule consisting of one selenium atom and four bromine atoms.

It's important to note that unlike ionic compounds, molecular compounds do not consist of charged ions, but rather neutral molecules. Therefore, when writing the chemical formula for a molecular compound, the aim is to represent the actual number of each type of atom present in the molecule, without having to balance charges, as you would with ionic compounds.

Inorganic Chemistry

Inorganic chemistry is the branch that deals with the synthesis, reactions, structures, and properties of inorganic compounds, which generally do not contain carbon-hydrogen (C-H) bonds. Compounds such as ionic salts, metals, minerals, and organometallic compounds fall under inorganic chemistry. Understanding inorganic compounds requires familiarity with periodic table trends, oxidation states, compound naming, and chemical reactions specific to non-organic chemistry.

In the context of writing chemical formulas, inorganic chemistry provides the grounding principles for understanding how different elements combine and interact with each other. For example, the formula for lead(IV) sulfide (PbS₂) reflects the lead ion's oxidation state and the sulfur ion's charge, principles that are fundamental to inorganic chemistry.