Names and Formulas for Ionic Compounds

In written names and formulas for ionic compounds, the cation appears first, followed by the anion. 

Real-World Reading Link Although people have a wide range of names, most have both a first name and a last name. Ionic compound names are similar, in that they also consist of two parts. 

Because chemists around the world need to be able to communicate with one another, they have developed a set of rules for naming compounds. Using this standardized naming system, you can write a chemical formula from a compound s name and name a compound given its chemical formula. 

Monatomic ions Binary ionic compounds are composed of positively charged monatomic ions of a metal and negatively charged monatomic ions of a nonmetal. A monatomic ion is a one-atom ion, such as Mg + or Br . Table 7.7 indicates the charges of common monatomic ions according to their location on the periodic table. What is the formula for the beryllium ion The iodide ion The nitride ion  

Transition metals, which are in groups 3 through 12, and metals in groups 13 and 14 are not included in Table 7.7 because of the variance in ionic charges of atoms in the groups. Most transition metals and metals in groups 13 and 14 can form several different positive ions. 

One of the most important requirements of chemistry is communicating information to others. Chemists discuss compounds by using both chemical formulas and names. The chemical formula and the name for the compound must be understood universally. Therefore, a set of rules is used in the naming of compounds. This system of naming allows everyone to write a chemical formula when given a compound name and to name the compound from a given chemical formula. 

Recall from Section 8.2 that a sample of an ionic compound contains crystals formed from many ions arranged in a pattern. Because no single particle of an ionic compound exists, ionic compounds are represented by a formula that provides the simplest ratio of the ions involved. The simplest ratio of the ions represented in an ionic compound is called a formula unit. For example, the formula KBr represents a formula unit for potassium bromide because potassium and bromide ions are in a one-to-one ratio in the compound. A formula unit of magnesium chloride is MgCl2 because two chloride ions exist for each magnesium ion in the compound. In the compound sodium phosphide, three sodium ions exist for every phosphide ion. What is the formula unit for sodium phosphide  

Because the total number of electrons gained by the nonmetallic atoms must equal the total number of electrons lost by the metallic atoms, the overall charge of a formula unit is zero. The formula unit for MgCl2 contains one Mg2+ ion and two Cl ions, for a total charge of zero. 

Group Atoms that commonly form ions Charge on ions 

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The charge of a monatomic ion is equal to its oxidation number. The oxidation number, or oxidation state, of an ion in an ionic compound is numerically equal to the number of electrons that were transferred to or from an atom of the element in forming the compound. If the electrons were transferred from the atom, the ion has a positive oxidation state. If they were transferred to the atom, the ion has a negative oxidation state. Most transition metals and metals of groups 3A and 4A can have more than one oxidation number. 

Oxidation numbers can be used to determine the chemical formulas for ionic compounds. If the oxidation number of each ion is multiplied by the number of that ion present in a formula unit, and then the results are added, the sum must be zero. 

In the formula for an ionic compound, the symbol of the cation is written before that of the anion. Subscripts, or small numbers written to the lower right of the chemical symbols, show the numbers of ions of each type present in a formula unit. 

Determine the correct chemical formula for the ionic compound formed from strontium (Sr) and bromine (Br). 

Write the correct formula for the ionic compound formed between atoms of each of the following pairs of elements. 

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Crafting names and formulas for ionic and molecular compounds Handling polyatomic ions Talking about acids... 

In writing formulas for ionic compounds from their names, we must remember the rules from Chapter 5. Be sure to balance the number of positive and negative charges The charges on the cations are implied for some cations (the constant type) and stated explicitly in the name for the others. The charge on a monatomic anion is equal to the group number minus 8 (see Section 5.2). 

You will name and write formulas for ionic compounds. 

Figure 8-8 reviews the steps used in naming ionic compounds if the formula is known. Naming ionic compounds is important in communicating the cation and anion present in a crystalhne solid or aqueous solution. How might you change the diagram to help you write the formulas for ionic compounds if you know their names ... 

Formulas are part of the language that is used to communicate information about substances. As a first step in studying this new language, you will learn how to name and write formulas for ionic compounds. 

Convert between the names and formulas for alcohols, binary covalent compounds, and ionic compounds. (Sections 3.3-3.5)... 

Copy and complete Table 4.A (below) by writing the names and formulas for the ionic compounds formed when the cations listed across the top combine with the anions shown in the left column. 

Use the two soluble ionic compounds as reactants. Write the names and formulas for the possible products of the reaction, along with the molecular equation and complete ionic equation. Is at least one of the products insoluble If so, go to step 5. If not, go back to step 2. 

Using the Stock system, the ferrous ion and the ferric ion are iron(II) and iron(III), respectively, so ferrous chloride becomes iron(II) chloride and ferric chloride is called iron(III) chloride. In keeping with modem practice, we will use the Stock system of naming compounds in this textbook. Examples 0.3 and 0.4 illustrate how to name and write formulas for ionic compounds based on the information given in Table 0.3. 

Write correct formulas for ionic compounds containing representative metals and polyatomic ions, and correctly name binary covalent compounds and compounds containing polyatomic ions. (Section 4.10)... 

Write formulas for ionic compounds that would form between the following simple ions. Note that the metal forms two different simple ions, and name each compound two ways. 

Sample Problems 2.9 and 2.10 illustrate how to name ionic compounds and write formulas for ionic compounds based on the information given in Figure 2.16 and Tables 2.8 and 2.9. 

Write the name and formula for an Ionic compound containing a polyatomic ion. 

Chapter 6, Ionic and Molecular Compounds, describes how atoms form ionic and covalent bonds. Chemical formulas are written, and ionic compounds— including those with polyatomic ions—and molecular compounds are named. An introduction to the three-dimensional shape of carbon molecules provides a basis for the shape of organic and biochemical compounds. Organic chemistry is introduced with the properties of inorganic and organic compounds and condensed structural formulas of alkanes. Section 6.1 is now tilled Ions Transfer of Electrons, 6.2 is titled Writing Formulas for Ionic Compounds, 6.3 is... 

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