Formula of an ionic compound lab

Module 3 Lab Experiment-Chimestry

Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise.

Experiment Summary:

You will apply the rules for naming ionic and molecular compounds to write the names of compounds when given the chemical formula. You will also write the formula for ionic and molecular compounds when given the name.

EXPERIMENT

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Learning Objectives Upon completion of this laboratory, you will be able to:

● Describe how the periodic table arranges elements by their chemical properties.

● Discuss the IUPAC naming system.

● Define molecular compound, ionic compound, polyatomic ion, oxidation state, and diatomic element.

● Identify the prefixes and suffixes used to name polyatomic ions and list the name, formula, and charge of common polyatomic ions.

● List the rules for converting formulas to names, and names to formulas for ionic and molecular compounds.

● Explain the difference between binary and oxoacids, and identify the rules for naming each.

● Generate a colored periodic table to distinguish between the groups of elements, and create a list of common polyatomic ions and strong acids to aid in naming chemical compounds.

● Write the names for ionic compounds, molecular compounds, polyatomic ions, and acids by interpreting their formulas.

● Write the chemical formula for ionic compounds, molecular compounds, polyatomic ions, and acids by interpreting their compound names.

Time Allocation: 3 hours

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Materials Student Supplied Materials

Quantity Item Description 1 Box of colored pencils or highlighters 1 Computer printer 1 Digital camera or smartphone 1 Package of note cards 1 Pen or pencil 1 Sheet of paper

Note: To fully and accurately complete all lab exercises, you will need access to:

1. A computer to upload digital camera images.

2. Basic photo editing software such as Microsoft® Word or PowerPoint®, to add labels, leader lines, or text to digital photos.

3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources.

Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit.

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Background The Periodic Table

The periodic table is a reference for the arrangement of chemical elements. See Figure 1. The periodic table not only organizes the elements by their atomic number and electron configurations, it also organizes the elements by their chemical properties. The periodic table is the most important tool to have on hand when studying chemistry. A periodic table is located on the inside cover of almost every chemistry textbook.

Figure 1. Periodic Table of Elements. Click to Download Printable Version.

Communication skills are important in any field, and the language of chemistry has a vocabulary of its own. In the medical field, it is essential to communicate clearly and effectively. For example, it is important to be correct and unambiguous when transferring responsibility for a patient to another person, or asking the doctor or dentist for required medication. Reports may be written for the doctor or for communicating with a patient about their condition, and learning how to write chemical names and formulas is the first step in pharmacology.

For example, the ionic compound potassium nitrite (KNO2) is used to treat chest pain, whereas the compound potassium nitrate (KNO3) is used to treat asthma and is also found in toothpastes for sensitive teeth. A pharmacologist or doctor would need to ensure the proper indication of these compounds to properly and effectively treat a patient’s symptoms.

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o http://holscience.com/sites/default/files/Periodic_Table.pdf\
The IUPAC Naming System

The International Union of Pure and Applied Chemistry (IUPAC) naming system provides a systematic method of naming compounds around the globe. The IUPAC naming system was designed with the fundamental principle that “each different compound should have a different name.” Each IUPAC name for organic compounds consists of several parts: 3D relationship, numbered substituents, number of carbons in the longest chain, and the ending suffix that describes functional groups. Figure 2 shows the molecular structure for vitamin C, also called ascorbic acid. The formal, IUPAC name for the chemical is (5R)-5-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one.

Figure 2. The unique IUPAC name for ascorbic acid (vitamin C) includes the numbered constituents, 3D relationship of atoms, the number of carbons, and functional groups.

©Macrovector

The IUPAC naming system assures safety and consistency when using chemicals. It would be difficult to replicate experiments if scientists used different names for the same compound. Safety would also be a concern if there was no consistent system for naming because of the various hazards associated with mixing chemicals.

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Naming Molecular Compounds

Molecular compounds consist of nonmetallic elements that share electrons through covalent bonds. The type of molecular compounds we will focus on naming in this lesson are binary molecular compounds. Binary molecular compounds consist of two nonmetal elements. For example, a water molecule (H2O) is a binary molecular compound consisting of the nonmetals hydrogen and oxygen.

To name a binary molecular compound, the first element is given its elemental name, and the second element is given its root (i.e. carb-, hydr-, ox-, fluor-) with the suffix “-ide.” For example:

● HF = hydrogen fluoride

Greek prefixes are used for molecular compounds to account for the number of each element in the compound. See Table 1 for the Greek prefixes that represent the numbers 1 - 10.

Table 1. Greek prefixes. Number of Atoms Prefix

1 Mono- 2 Di- 3 Tri- 4 Tetra- 5 Penta- 6 Hexa- 7 Hepta- 8 Octa- 9 Nona-

10 Deca-

For example:

● CO2 = carbon dioxide

● N2O3 = dinitrogen trioxide

The prefix “mono-” is never used for the first element, and only used for the second element if ambiguity exists in the naming. A few examples for using the prefix “mono-” on the second element are:

● carbon monoxide

● dinitrogen monoxide

● nitrogen monoxide

Note: If the final vowel in a prefix is “a” or “o” it is dropped before the vowel in a stem name, for ease of pronunciation.

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Converting a Molecular Compound Formula to a Name

Example 1: Writing a Nonmetal + Nonmetal Name: P2S5 1. Read the formula and look at the subscripts.

P2S5

Note that P and S are nonmetals, which can be determined by referencing a periodic table like the one in Figure 1.

2. Write the name of the first element with the correct Greek prefix.

P2 = diphosphorus

3. Write the root name of the second element with the suffix “-ide.”

S = sulfur = sulfide

4. Write the correct Greek prefix of the second element.

S5 = pentasulfide

5. Write the name of the molecular compound.

P2S5 = diphosphorus pentasulfide

Example 2: Writing a Nonmetal + Nonmetal Name: CO

1. Read the formula and look at the subscripts.

CO

2. Write the name of the first element with the correct Greek prefix. If the 1st element has the prefix “mono”, it is dropped.

C = carbon (NOT monocarbon)

3. Write the root name of the second element with the suffix “-ide.”

O = oxygen = oxide

4. Write the correct Greek prefix of the second element. If the final vowel in a prefix is “a” or “o” it is dropped before the vowel in a stem name, for ease of pronunciation.

O = monoxide (NOT monooxide)

5. Write the name of the molecular compound.

CO = carbon monoxide

Note: There is no charge indicated in the above formulas which indicates that they are molecular compounds and not ionic compounds.

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Converting a Name to a Molecular Compound Formula

Example 3: Writing a Nonmetal + Nonmetal Formula: Carbon Tetrafluoride

1. Read the name of the compound. carbon tetrafluoride

2. Write the first chemical symbol based on the first name written in the compound. carbon = C

3. Include the number of atoms based on the prefix (if any) included in the first name. 1 carbon atom = C

Note: Since the word “carbon” in carbon tetrafluoride has no prefix, it can be assumed that there is only one carbon atom in the molecule.

4. Write the second chemical symbol based on the second name written in the compound. fluoride = fluorine = F

5. Include the number of atoms based on the prefix (if any) included in the second name. tetrafluoride = 4 fluorine atoms = F4

6. Write the formula of the molecular compound. carbon tetrafluoride = CF4

Note: You will not be asked to “balance” the formula of molecular compounds because there are no ions to balance. Ionic charges and balancing equations will be introduced later.

Example 4: Writing a Nonmetal + Nonmetal Formula: Diboron Trioxide

1. Read the name of the compound. diboron trioxide

2. Write the first chemical symbol based on the first name written in the compound. boron = B

3. Include the number of atoms based on the prefix (if any) included in the first name. diboron = 2 boron atoms = B2

4. Write the second chemical symbol based on the second name written in the compound. oxide = oxygen = O

5. Include the number of atoms based on the prefix (if any) included in the second name.

trioxide = 3 oxygen atoms = O3

6. Write the formula of the molecular compound. diboron trioxide = B2O3

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Naming Ionic Compounds

Ionic compounds are chemical compounds containing both a cation (positive ion) and an anion (negative ion) held together by electrostatic forces, also known as ionic bonds. Ionic compounds are different from molecular compounds in that they usually contain a metal or an ammonium ion (NH4

+) and molecular compounds are composed of nonmetals. A binary ionic compound contains two elements, one metal and one nonmetal.

To name a binary ionic compound, the cation elemental name is listed first, followed by the root of the anion ending in “-ide.” For example:

● NaCl = sodium chloride

Greek prefixes are not used in naming the number of atoms of each element for ionic compounds. For example:

● Li3N = lithium nitride, NOT trilithium nitride.

Ionic compounds are written as neutral compounds, meaning the overall charge of the compound must equal zero. In order to determine the overall charge, the oxidation state of the metal and nonmetal must be known in order to ensure the correct number of atoms of each element are present in the compound. The oxidation state represents the number of electrons that an atom can gain, lose, or share when bonded with an atom of another element. The oxidation state for each element can be found on the periodic table in Figure 1. We will discuss how to use the oxidation state to calculate the number of atoms of a compound in further detail later.

Converting an Ionic Compound Formula to a Name

1. Use the periodic table to determine if a metal is present in the compound.

Note: Be aware that many elements have similar names and symbols.

a. If a metal is present, the compound is likely an ionic compound.

2. Determine if the metal ion (cation) has a “fixed charge.” A fixed charge means that there is only one possible oxidation state, as shown in Figure 3. Cations with a fixed charge include.

a. All elements in Group IA and Group IIA

b. Al3+

c. Transition metals with a fixed charge: Ag1+, Zn2+, and Cd2+

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Figure 3. The fixed charge oxidation states, or charges, of the element potassium (K) in Group IA and the element beryllium (Be) in Group IIA.

3. Proceed to step 6 if the metal does not have a fixed charge, otherwise continue to step 4.

4. Name the cation first.

a. Record the entire name of the cation.

5. Name the anion second.

a. Combine the root name of the nonmetal anion with the suffix “-ide.” The conversion from a formula to a name is complete once the anion has been named.

6. Determine the variable charges for the metal, as shown in Figure 4. Variable charge means that there is more than one possible oxidation state. Elements with a variable charge include:

a. All transition metals in Groups IIIA through IIB, EXCEPT: Ag1+, Zn2+, and Cd2+

b. All basic metals EXCEPT: Al3+

Figure 4. The variable charge oxidation states, or charges, that iron (Fe) and gold (Au) can carry.

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7. Name the cation first.

a. Include the entire name of the cation.

b. Balance the ionic charges of the cation and anion. Identify the number of ions required to generate a neutral compound.

c. List the Roman numeral in parentheses based on the ionic charge. Do not put a space between the cation name and the parentheses. For example, iron(III) chloride.

8. Name the anion second.

a. Include the root name of the anion and the suffix “-ide.”

Example 5: Writing a Metal + Nonmetal Name: Li2O

1. Read the formula and look at the subscripts.

Li2O

Note that Li is a metal and O is a nonmetal, which can be determined by referencing a periodic table like the one in Figure 1.

2. Determine if the metal ion has a fixed charge or variable charge.

Li = Group IA = fixed charge = 1+

3. Record the entire name of the cation.

Li = lithium

4. Write the root name of the nonmetal ion with the suffix “-ide.”

O = oxygen = oxide

5. Write the name of the ionic compound.

lithium oxide

Example 6: Writing a Metal + Nonmetal Name: Fe2O3 1. Read the formula and look at the subscripts.

Fe2O3 2. Determine if the metal ion has a fixed charge or variable charge.

Fe = Group VIIIB = variable charge = 2+ or 3+

3. Record the entire name of the cation.

Fe = iron

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4. Determine the Roman numeral by balancing the charges to create a neutral compound.

a. There are 2 atoms of iron and 3 atoms of oxygen.

b. We know oxygen always carries a 2- charge so all 3 atoms of oxygen have a 2- charge.

c. We need to determine if each iron atom has a 2+ or a 3+ charge by a simple algebraic calculation where the charge for each iron atom equals x and the equation is set to 0:

Tip: To balance Fe2O3, first consider the oxygen atoms. Oxygen always has a charge of 2-, therefore O3 has a total charge of 6-. This means that Fe2 must have a total charge of 6+. Each F atom will have a charge of 3+.

d. After solving for x, we find that each iron atom carries a 3+ charge. Thus, the Roman numeral used in the compound name is “III.”

iron(III)

5. Write the root name of the nonmetal ion with the suffix “-ide.”

O = oxygen = oxide

6. Write the name of the ionic compound.

iron(III) oxide

Converting a Name to an Ionic Compound Formula

When writing formulas for ionic compounds, the sum of the positive and negative charges MUST equal zero to obtain a neutral compound.

Example 7: Writing a Metal + Nonmetal Formula: Calcium Fluoride

1. Read the name of the compound.

calcium fluoride

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2. Determine if the metal ion has a fixed charge or variable charge.

calcium = Group IIA = fixed charge = 2+

Note: If the name does not include a Roman numeral, then the metal ion has a fixed charge.

3. Write the first chemical symbol based on the cation in the compound, including the charge.

calcium = Ca2+

4. Write the second chemical symbol based on the anion in the compound, including the charge.

fluoride = fluorine = F-

5. Balance the charges to determine the correct number of atoms of each element and write the formula for a neutral compound.

Tip: To balance CaF2, first consider the Ca has a fixed charge of 2+ and F carries a 1- charge. For the compound to have a net charge of 0, there must be two F atoms and one Ca atom.

6. Write the formula of the molecular compound.

calcium fluoride = CaF2

Example 8: Writing a Metal + Nonmetal Formula: Gold(III) Chloride

1. Read the name of the compound.

gold(III) chloride

2. Determine if the metal ion has a fixed charge or variable charge.

gold = Group IB = variable charge = 1+ or 3+

3. Write the first chemical symbol based on the cation in the compound, including the charge. The name tells us it is gold(III) meaning it carries a 3+ charge:

gold(III) = Au3+

4. Write the second chemical symbol based on the anion in the compound, including the charge.

chloride = chlorine = Cl-

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5. Balance the charges to determine the correct number of atoms of each element to write the formula for a neutral compound.

6. Write the formula of the molecular compound.

gold(III) chloride = AuCl3

Polyatomic Ions

Polyatomic ions are a group of two or more covalently bonded atoms that function as a single ion. For example, oxygen carries a 2- charge and hydrogen carries a 1+ charge. When combined they form a covalent bond, producing a single anion with a 1- charge called hydroxide (OH-). The 1- charge of the hydroxide ion is a product of the 2- charge of the O with the 1+ charge of the H (-2 + 1 = -1). Polyatomic ions are the fundamental unit in the majority of ionic compounds; therefore, knowing polyatomic ion names, formulas, and charges is important. Common ions and their charges are listed in Table 2.

Table 2. Common polyatomic ions.

Name Formula Charge

Ammonium NH4 + 1+

Hydroxide OH- 1-

Cyanide CN- 1-

Nitrite** NO2 - 1-

Nitrate** NO3 - 1-

Sulfite** SO3 2- 2-

Sulfate** SO4 2- 2-

Hydrogen sulfite** HSO3 - 1-

Hydrogen sulfate** HSO4 - 1-

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Name Formula Charge

Carbonate CO3 2- 2-

Hydrogen carbonate HCO3 - 1-

Phosphate PO4 3- 3-

Hydrogen phosphate HPO4 2- 2-

Dihydrogen phosphate H2PO4 - 1-

Hypochlorite ClO- 1-

Chlorite** ClO2 - 1-

Chlorate** ClO3 - 1-

Perchlorate ClO4 - 1-

Peroxide O2 2- 2-

Chromate*** CrO4 2- 2-

Dichromate*** Cr2O7 2- 2-

Permanganate*** MnO4 - 1-

**Note the very subtle differences in names and subscripts due to the oxidation states.

*** Note that permanganate, chromate, and dichromate each have a metal and a nonmetal.

Note: There are additional tables of polyatomic ions available online and in textbooks. This table includes only the most common ions encountered in general chemistry classes.

Here are a few helpful hints for naming polyatomic ions:

a. Suffixes: the name of the ion usually ends in “-ite” or “-ate.” A low oxidation state will have an ion ending in “-ite,” versus a higher oxidation state that ends in “-ate.” The oxidation state is dependent upon a calculation of the charges of the polyatomic ion. Figure 5 shows the calculations of the oxidation state for the sulfite ion (SO3

2-) and the sulfate ion (SO4

2-). A simple algebraic calculation is done to determine the oxidation state for each polyatomic ion by solving for “x” since we know that oxygen (O) carries a 2- charge:

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Figure 5. Algebraic calculations for the oxidation state of the polyatomic ions sulfite and sulfate.

b. Prefixes: “hypo-” indicates the very lowest oxidation state and “per-” indicates the very highest oxidation state. Figure 6 shows the calculations of the oxidation state for the hypochlorite ion (ClO-) and the perchlorate ion (ClO4

-). A simple algebraic calculation is done to determine the oxidation state for each polyatomic ion by solving for “x” since we know that oxygen (O) carries a 2- charge:

Figure 6. Algebraic calculations for the oxidation state of the polyatomic ions hypochlorite and perchlorate.

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c. Few polyatomic ions have positive charges. These ions have names ending in “-onium.” For example, ammonium (NH4

+) and hydronium (H3O +).

d. There are a few exceptions to these rules. The following polyatomic ions were once thought to be monatomic ions so they end in “-ide:” hydroxide (OH-), cyanide (CN-), and peroxide (O2

2-).

Naming Polyatomic Ion Compounds

Example 9: Writing a Metal + Polyatomic Ion Name: KNO2 1. Read the formula and look at the subscripts.

KNO2 2. Determine if the metal ion has a fixed charge or variable charge.

K = Group IA = fixed charge = 1+

3. Record the entire name of the cation.

K = potassium

4. Record the entire name of the anion.

NO2 = nitrite

5. Write the name of the ionic compound.

potassium nitrite

Example 10: Writing a Metal + Polyatomic Ion Formula: Gold(I) Nitrate

1. Read the name of the compound.

gold(I) nitrate

2. Determine if the metal ion has a fixed charge or variable charge.

gold = Group IB = variable charge = 1+ or 3+

3. Write the first chemical symbol based on the cation in the compound, including the charge. The name tells us it is gold(I) meaning it carries a 1+ charge.

gold(I) = Au+

4. Write the second chemical symbol based on the anion in the compound, including the charge.

nitrate ion = NO3 -

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5. Balance the charges to determine the correct number of atoms of each element to write the formula for a neutral compound.

6. Write the formula of the molecular compound.

gold(I) nitrate = AuNO3

Naming Acids

Simple covalent compounds that contain hydrogen often dissolve in water to produce acids. For example, HF in its gaseous state (g) is hydrogen fluoride, but HF in aqueous solution (aq) is hydrofluoric acid. This lesson focuses on binary acids and oxoacids. Binary acids are acids in which hydrogen bonds with a second nonmetallic element. An oxoacid is an acid containing oxygen, hydrogen, and a third element. An oxoacid contains at least one hydrogen atom bound to the oxygen. These acids dissociate in water by breaking the OH bond to form a H+ ion and an anion.

There are a unique set of rules for naming both binary and oxoacids. The systematic names for binary acids include the prefix “hydro-” (indicating the water the acid is dissolved in) and the root of the second element’s name (the non-metal). The suffix of the anion changes from “-ide” to “-ic,” followed by the word “acid.” For example:

water + H+ + F- = HF(aq) = hydrofluoric acid

Note: Acids containing sulfur use the full name “sulfur” instead of the root of the name. For example, H2S(aq) is called hydrosulfuric acid NOT hydrosulfic acid.

Oxoacids are named based on the nonmetal from which they are derived. The prefix “hydro-” is not used, and the suffix “-ate” is changed to “-ic,” and the suffix “-ite” is changed to “-ous.” For example, HNO3 (contains the nitrate ion) is named nitric acid. The prefixes used for lowest and highest oxidation states are also used in the naming of oxoacids. For example, HClO (contains the hypochlorite ion) is named hypochlorous acid. See Table 3 for examples of formulas and names for strong acids that may be encountered.

Note: Since acids are covalent compounds dissolved in water, the formula must indicate the physical state the compound is in to distinguish it from covalent compounds NOT dissolved in water. For example, HCl(g) is hydrogen chloride whereas HCl(aq) is hydrochloric acid.

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Table 3. The formulas and systematic names for a selection of common strong acids.

Acid Formula Non-metal Present in Acid Systematic Name HCl(aq) Chloride Hydrochloric acid HBr(aq) Bromide Hydrobromic acid HI(aq) Iodide Hydroiodic acid

HNO3(aq) Nitrate Nitric acid H2SO4(aq) Sulfate Sulfuric acid

Diatomic Elements

Diatomic elements do not have full valence electron shells and cannot exist as a single atom. For example, the reactivity of hydrogen causes lone atoms to combine into diatomic (two atom) molecules forming hydrogen gas (H2(g)) or liquid hydrogen (H2(l)). Element names ending in “-gen” or “-ine” are diatomic. The names and formulas for the seven diatomic elements can be found in Table 4.

Note: These elements are diatomic ONLY when they are the only element present, NOT when they are chemically bonded to other elements.

Table 4. The formulas and names of the seven diatomic elements.

Seven Diatomic Elements

Hydrogen H2 Nitrogen N2 Oxygen O2 Fluorine F2 Chlorine Cl2

Bromine Br2

Iodine I2

Review and Tips

In the Exercises, you will study the periodic table and familiarize yourself with polyatomic ions, common acids, and the diatomic elements. Then, you will practice the discipline of following a set of rules to write the names and formulas of ionic and molecular compounds. It is important to follow all of the rules and not to skip steps. Do not go too fast, or guess at names, charges, or formulas. If you guess incorrectly you may learn or memorize the rules incorrectly. Review the flowchart in Figure 7 for help differentiating between molecular and ionic compounds.

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Figure 7. Flowchart for naming ionic and molecular compounds.

The following tips will help you in the coming Exercises:

1. If there is no metal present in the compound, the compound is likely a molecular compound.

2. One way to distinguish between binary ionic compounds and binary molecular compounds is to look for a prefix. Molecular compounds use a Greek prefix to indicate the number of each atom in the compound. Refer to Table 1.

3. When naming ionic compounds (a metal and a nonmetal or polyatomic ion), if the metal ion is in Group IA or IIA, or one of the following elements: Ag, Zn, Cd, or Al, then the cation is named first. The anion is named second: monoatomic ions have the suffix “-ide,” and polyatomic ions have no suffix.

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4. If the metal is in Groups IIIA through IIB (EXCEPT for Ag, Zn, Cd, or Al) then the ionic compound is named as in step 3, except a Roman numeral is added in parentheses after the metal name to indicate the charge of the metal ion.

5. When writing the formula for ionic compounds, write the symbol for the cation first, followed by the anion.

6. EVERY time a compound contains a metal, balance the charges of the compound when writing the formula.

7. Print or write down the steps on naming ionic and molecular compounds in the Background, and use them for every example.

8. An aqueous physical state distinguishes binary acids from simple molecular compounds.

9. Double check your work. After you have written the name of a chemical compound, cover the name and try to write the corresponding formula, and vice versa.

10. Use the note cards that will be created in Exercise 1 for every compound in Exercise 2.

Practicing is the best way to learn how to name chemical compounds and write the corresponding formulas.

Chemists can have a sense of humor at times when naming

molecules. Some of the more classroom “appropriate” include, Draculin which is a

large glycoprotein found in vampire bat saliva. Penguinone, named from its similarity in 2D

structure to a penguin. The keto acid of morolic acid, isolated from the mora tree, is named moronic acid with derivatives called moronates, as in “which moron-ate all of the pie?” Traumatic acid is a plant hormone that causes injured cells to divide and help repair trauma to the plant. Uranium has resulted in

the creation of numerous silly names such as the uranium oxide anions known as urinates, uranium

nitrate which is also known as uranyl nitrate, and U4+ known as the uranous ion.

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Exercise 1: Preparation for Naming Ionic and Molecular Compounds In this exercise, you will color the periodic table and prepare note cards to learn common polyatomic ions and acids. You will also review tips for correctly naming ionic and molecular compounds.

Procedure

1. Print the Periodic Table of Elements found here http://holscience.com/sites/default/files/ PeriodicTable.pdf.

2. Use colored pencils or photo editing software (i.e. Paint®, Microsoft Powerpoint®, Adobe Photoshop®) to color the groups of elements referenced in the legend boxes. Each group of elements should be represented by a unique color.

3. Color the legend boxes with the corresponding color used for each group.

4. Record your name and the date on the table. Then, take a photo of the colored periodic table, or save it as an image if you use photo editing software.

5. Resize and insert the image into Data Table 1 of your Lab Report Assistant. Refer to the appendix entitled “Resizing an Image” for guidance.

6. Write the name, formula, and charge for each of the common polyatomic ions in Table 2 of the Background onto individual note cards. Polyatomic ions that vary based on oxidation state, such as sulfate and sulfite, can be included on the same card, as shown in Figure 8.

Figure 8. Note card with two polyatomic ions the vary based on oxidation state.

7. Take a photo of a completed note card.

8. Resize and insert the image into Data Table 1.

9. Write the systematic name and formula for each of the strong acids in Table 3 of the Background on a note card.

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10. Take a photo of the completed note card of the common strong acids.

11. Resize and insert the image into Data Table 1.

12. Write the name and formula for each of the seven diatomic elements in Table 4 of the Background on a note card.

13. Take a photo of the completed note card of diatomic elements.

14. Resize and insert the image into Data Table 1.

15. Review the note cards (polyatomic ions, strong acids, and diatomic elements) until you are familiar with the content. You will reference the note cards in the next exercise.

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Exercise 2: Naming Ionic and Molecular Compounds In this exercise, you will practice naming and writing the formula for ionic and molecular compounds.

Procedure

Note: Reference the procedures, figures, and tables in the Background to successfully complete this Exercise.

Part 1: Molecular and Ionic Compounds

1. View the first formula in Data Table 2 of your Lab Report Assistant.

a. Determine if the compound is molecular or ionic and record in Data Table 2.

b. If the compound is molecular, record the name of the first element with the correct prefix, followed by the prefix for the second element. Then add -ide to the root of the second element.

c. If the compound is ionic, determine if the metal ion (cation) has a fixed or variable charge. Record the name of the cation followed by the root name of the anion with the suffix “-ide” if the anion is only one type of element, or the full name of the polyatomic ion. For cations with a variable charge, be sure to include the correct Roman numeral to record the name of a neutral compound by ensuring the sum of the charges for the anion and the cation equal 0.

2. Repeat step 1 for the remaining formulas in Data Table 2.

3. View the name for the first compound in Data Table 3 of your Lab Report Assistant.

a. Determine if the compound is molecular or ionic and record in Data Table 3.

b. If the compound is molecular, record the chemical symbol of the first and second elements. Include the correct number of atoms based on the prefix (if any) given in the name.

c. If the compound is ionic, determine if the metal ion (cation) has a fixed or variable charge. Record the chemical symbol of the cation and anion. Be sure to include the correct number of atoms to record the formula of a neutral compound by ensuring the sum of the charges for the anion and the cation equal 0.

4. Repeat step 3 for the remaining compounds in Data Table 3.

Part 2: Polyatomic Ions and Acids

5. Record the name of the first compound in Data Table 4 of your Lab Report Assistant.

a. Determine if a cation or hydrogen is present in the compound. For cations with a variable charge, include the correct Roman numeral to record the name of a neutral compound by ensuring the sum of the charges for the polyatomic ion and the cation equal 0.

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Experiment Naming Ionic and Molecular Compounds

b. If the compound contains a hydrogen and occurs in its aqueous state, record the systematic acid name. Binary acids will include “hydro-” to indicate water, followed by the root of the second element ending with the suffix “-ic” and the word “acid.” Oxoacids will not include the prefix “hydro” and the suffixes and any prefixes (if needed) will depend on the anion present in the compound.

c. Determine the corresponding polyatomic ion and change the suffix as necessary.

d. Refer to the note cards created in Exercise 1 for oxidation states, the names of common polyatomic ions, and suffix changes for acids.

6. Repeat step 5 for the remaining compounds in Data Table 4.

7. Record the chemical formula for the first compound in Data Table 5 of your Lab Report Assistant.

a. Record the chemical symbol of the first metal ion or hydrogen (if any). Include the correct number of atoms based on the prefix (if any) given in the name. Include the physical state to distinguish binary acids from simple molecular compounds.

b. For cations, include the correct number of atoms to record the formula of a neutral compound by ensuring the sum of the charges for the polyatomic ion and the cation equal 0.

c. If the compound is an acid, the formula will contain a hydrogen followed by the second element(s) depending on if it is a binary or an oxoacid.

d. Refer to Table 2 from the Background for the charges and the formulas of common polyatomic ions.

8. Repeat step 7 for the remaining compounds in Data Table 5.

Questions A. Determine the effect of adding H+ to the polyatomic ion phosphate such that it produces a

neutral compound. Indicate the effect on the charge and record the new name.

B. The metals in group IIIA, IVA, and VA of the periodic table are not transition metals. However, all but 1 have variable charges. What element in Group IIIA, period 3 has a fixed charge, and what is that charge?

C. Describe the difference between molecular and ionic compounds.