Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

VocabularyBinaryCarbon atomCarbon dioxideEmpirical formulaFossil fuel

HydrocarbonsIsomersMoleMolecular formulaOrganic matter

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

Code Unit 5-Nomenclature & Formula Stoichiometry Textbook Reference

C4.1x Molecular and Empirical Formulae Compounds have a fixed percent elemental composition. For a compound, the empirical formula can be calculated from the percent composition or the mass of each element. To determine the molecular formula from the empirical formula, the molar mass of the substance must also be known.

*C4.1a Calculate the percent by weight of each element in a compound based on the compound formula.

C4.1b Calculate the empirical formula of a compound based on the percent by weight of each element in the compound.

C4.1c Use the empirical formula and molecular weight of a compound to determine the molecular formula.

C4.2 Nomenclature All compounds have unique names that are determined systematically.*C4.2A Name simple binary compounds using their formulae.*C4.2B Given the name, write the formula of simple binary compounds.C4.2x Nomenclature All molecular and ionic compounds have unique names that are

determined systematically.*C4.2c Given a formula, name the compound.*C4.2d Given the name, write the formula of ionic and molecular compounds.C4.2e Given the formula for a simple hydrocarbon, draw and name the isomers.C4.6x Moles The mole is the standard unit for counting atomic and molecular particles in terms

of common mass units.*C4.6a Calculate the number of moles of any compound or element given the mass of the

substance.*C4.6b Calculate the number of particles of any compound or element given the mass of the

substance.*Priority Expectations

C.4.1a, C4.1b, C4.1c: Percent Composition, Empirical Formula, and Molecular Weight: Percent Composition: https://youtu.be/lywmGCfIUIA

Percent Composition: The relative amount of each element in a compound is called the percent composition. Remember the formula for calculating the percent is:

Part X 100 = %Whole

The part in this case will be the element of interest (for example Na) and the whole will be the compound (the Na in NaCl).To calculate the percent composition you have to:

1) Calculate molecular mass or formula mass of the compound.2) Calculate the mass of the element of interest.3) Calculate the percentage:

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________Example 1: Calculate the percent of Na in NaCl.

Example 2: Calculate the percent composition of NaCl.

Example 3: Calculate the percent composition of Na2SO4.

Practice Skill: 1. Calculate the percent composition of H2SO4.

2. Calculate the percent composition of Na2CO3.

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________3. Calculate the percent of MgSO4 • 7 H2O.

4. Calculate the percent composition of carbon atoms in ethane, C2H6.

A. 28.5%B. 80.0%C. 39.9%D. 60.1%

5. Find the percentage of sulfur in H2SO4.

A. 32.65%B. 85.04%C. 60.25%D. 74.19%

6. Find the percent composition of Cu in CuSO4·5 H2O.

A. 40%B. 26%C. 12%D. 35%

Empirical Formula: http://www.chem.tamu.edu/class/majors/tutorialnotefiles/empirical.htmThe empirical formula is a formula that gives the simplest whole number ration of atoms in a compound. For example benzene C6H6 and ethyne C2H2 both have the same empirical formula CH, a 1:1 ratio of C to H. For many substances, the empirical formula is the only formula possible such as water H2O, a ratio of 2:1 two H to one O, or carbon monoxide CO, a 1:1 ratio of C to O.

Calculating the Empirical Formula:

1. PERCENT TO MASS: Start with the number of grams of each element, given in the problem.  o If percentages are given, assume that the total mass is 100 grams so that the mass of each

element = the percent given.2. MASS TO MOLE: Convert the mass of each element to moles using the molar mass from the periodic

table: https://youtu.be/VAyGe_fW3FE4

Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________3. DIVIDE BY SMALL: Divide each mole value by the smallest number of moles calculated.  4. TIMES ‘TILL WHOLE: Round to the nearest whole number.  This is the mole ratio of the elements

and is represented by subscripts in the empirical formula.  o If the number is too far to round (x.1 ~ x.9), then multiply each solution by the same factor to get

the lowest whole number multiple.  e.g.  If one solution is 1.5, then multiply each solution in the problem by 2 to get 3.  e.g.  If one solution is 1.25, then multiply each solution in the problem by 4 to get 5. 

Example 1: NutraSweet is 57.14% C, 6.16% H, 9.52% N, and 27.18% O.  Calculate the empirical formula of NutraSweet. 

PERCENT TO MASS: Rewrite each percentage as grams, you assume you have a 100 g sample.

MASS TO MOLE: Convert the mass of each element to moles using the molar mass from the periodic table.

DIVIDE BY SMALL: Divide each mole value by the smallest number of moles calculated.  TIMES ‘TILL WHOLE: You need to have whole numbers, if you end up with a .5 multiply it by 2 to get a whole number.

This is the mole ratio of the elements and is represented by subscripts in the empirical formula. If you have to convert a decimal like 2.5 into a whole number by multiplying by 2 then you would have to multiply all by 2.

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

Practice Skill: Find the empirical formulas for the following substances: 1. 88.8% copper, 11.2% oxygen

2.  40.0% carbon, 6.7% hydrogen, 53.3% oxygen

3. Given: Ba = 58.81%, S = 13.73% and O = 27.46%. Find the empirical formula.

A. BaS2O4

B. Ba3SO5

C. BaSO4

D. Ba4SO

4. What is the empirical formula of a compound that is 40% sulfur and 60% oxygen by weight?

A. SOB. SOC. SOD. S O

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________Using the empirical formula & molar mass to determine the molecular formula; If the empirical formula and the mass of the compound are known, the molecular formula can be determined.

1. Calculate the mass of the empirical formula 2. Set up a ratio; divide molar mass of the compound by mass of the empirical formula 3. Multiply all the atoms (subscripts) by this ratio to find the molecular formula. 

Example 1: The empirical formula of glucose is CH2O, calculate the molecular formula. The molar mass of glucose is 180 g/mol.

Practice Skill: 1. A compound with an empirical formula of CH has a molecular weight of 78 g/mol. What is the molecular formula?

2. The empirical formula for caffeine is C4H5N2O and the molar mass of caffeine is 194.19 g/mol. Find the molecular formula for caffeine.

3. A compound has an empirical formula of P2O5. The molecular weight of the compound is 283.88 g. What is the molecular formula for this compound?

A. PO2

B. P2O5

C. P4O5

D. P4O10

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________C4.2A, C4.2B: Nomenclature-All compounds (metal---nonmetal) have unique names that are determined systematically: https://youtu.be/9XUsOLaz3zY

Naming Simple Ionic Compounds using their Formula: Positively charged ions are called cations (these are metals that lose electrons) and negatively charged ions are called anions (these are nonmetals that gain electrons). Look at your periodic table or a common ion chart for oxidation states.

Hydrogen can also form a cation, H+, in which case the name hydrogen is used in naming.

For metals that have only one possible charge (groups 1, 2, and 13) the name of the metal is used.

Transitional metals can have more than one charge (groups 3-12). The name of the metal will be followed by a Roman numeral corresponding to the oxidation number.

Negatively charged elements have the suffix – ide. Examples are oxide (O2-), sulfide (S2-), fluoride (F-), chloride (Cl-), bromide (Br-), iodide (I-), nitride (N3-), hydride (H-).

1. When positive ions and negative ions form a bond all charges must equal zero

2. The metal comes first, its name does not change

3. The nonmetal comes second, its suffix changes to “ide”

Example 1: Ionic Compounds with Ions of Elements8

Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

MgO CATION: Mg2+ is named magnesium it belongs to Column 2 and always carries a charge of 2+ ANION: O2- is named oxide it belongs to Column 16 and always carries a charge of 2-Name of compound is magnesium oxide

FeS CATION: Fe2+ is named iron (II), iron is a transitional metal and these charges vary but you know sulfur has a definite charge of 2-, so this means iron must carry a charge of 2+ in order to cancel the 2- charge.ANION: S2- is named as sulfide Name of compound is iron (II) sulfide

Practice Skill: Name the following simple binary compounds using their formula.

http://screencast.com/t/0oMIoFedLz and http://screencast.com/t/abgpwnED3

1. LiCl ______________________________________________________________

2. Li2O ______________________________________________________________

3. MgBr2____________________________________________________________

4. Fe2S3_________________________________________________________________

5. CuCl__________________________________________________________________

6. CuO___________________________________________________________________

Given the Name, Write the Formula of Ionic Compounds:

Writing formulas for simple binary compounds: https://youtu.be/ACW9FtX2oRY or https://youtu.be/vscoYh6m46M

1. Look at the name of the metal, locate its charge on your common ion chart2. Look at the name of the nonmetal, locate its charge on your common ion chart3. Place the two next to each other and use the criss cross method—remember to reduce to lowest terms

and that a number of 1 does not have to be written down

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________Examples:

1. What is the formula for Aluminum Oxide?

2. What is the formula for Lithium Oxide? 3. What is the formula for Iron (II) Oxide?

Practice Skill: Given the name write the formula of ionic compounds.

http://screencast.com/t/T3il9hfudH and http://screencast.com/t/pXEVl8Tz7Ot

1. Lithium Chloride __________________________________

2. Calcium Oxide _____________________________________

3. Magnesium Bromide_________________________________

4. Iron (III) Sulfide_____________________________________

5. Sodium Nitride ____________________________________

6. Mercury (I) Oxide______________________________________

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________C4.2c, C4.2d, C4.2e: Nomenclature-All molecular and ionic compounds have unique names that are determined systematically.

C4.2c: Given the formula name the compound; now we will look at polyatomic ions and molecular compounds.

Cations can be metals or polyatomic ions: The ammonium ion (NH4+) is an example of a polyatomic cation.

Polyatomic ions which include oxygen in the anion have the suffixes –ate or ite. “ate” means there is more oxygen in the anion than one ending in “ite”.

Examples: sulfate (SO42-) has more oxygen than sulfite (SO3

2-), nitrate (NO3-) has more oxygen in

the anion than nitrite (NO2-)

Exception: OH- is named hydroxide

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

Given a formula write the name: https://youtu.be/7ztVqRbwu4Q

1. When positive ions and negative ions form a bond all charges must equal zero

2. The metal comes first, its name does not change

3. The nonmetal comes second, its suffix changes to “ide”

4. Look at your chart for the names of polyatomic ions

Example 1: Ionic Compounds with Polyatomic Ions

NaOH CATION: Na+ is named as sodium ANION: OH- is named as hydroxide Name of compound is sodium hydroxide

CaCO3 CATION: Ca2+ is named as calcium ANION: CO3

2- is named as carbonate Name of compound is calcium carbonate

FeSO4 CATION: Fe2+ named as iron (II) because sulfate carries a charge of 2- so 2+ will cancel it outANION: SO4

2- named as sulfate Name of compound is iron (II) sulfate

(NH4)3PO4 CATION: NH4

+ named as ammonium ANION: PO4

3- named as phosphate Name of compound is ammonium phosphate

Practice Skill: Name the following Ionic Compounds with Polyatomic Ions.

1. NaClO3________________________________________________________________

2. Al2(SO4)3______________________________________________________________

3. NH4OH________________________________________________________________

4. FeSO3 _______________________________________________________________

5. Hg(HSO4)2___________________________________________________________

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________6. ZnCO3_________________________________________________________________

Given covalent formula write the name: https://youtu.be/VokWJy_jpAc

For a molecular compound (nonmetal—nonmetal) you simply use Greek prefixes.

The element with the lowest electronegativity will go first; its name does not change. The name of the second atom with the highest electronegativity changes to a suffix ending in “ide”.

1. Look at the first atom, if there is more than one of them write the Greek prefix followed by the name of the atom

2. Look at the second atom, if there is more than one of them write the Greek prefix followed by changing the name of the atom to end in “ide”

Examples:

A. CO Carbon Monoxide

B. N2O4 Dinitrogen Tetraoxide

Practice Skill: Write the name of the formula for a molecular (covalent) bond.

1. NO____________________________________________________________________

2. N2O4__________________________________________________________________

3. P2O5___________________________________________________________________

4. PCl5____________________________________________________________________

5. NO2____________________________________________________________________

6. N2O____________________________________________________________________

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

C4.2d: Given the name write the formula:

For ionic compounds look at your common ion chart to match the name with the polyatomic ion and its charge then use the crisscross method.

Example: Aluminum Sulfate

Note with polyatomic ions if you have more than one you need parentheses.

For covalent compounds look at the first name of the atom and write its symbol followed by a subscript number if there is a Greek prefix. Do the same for the second atom.

Example: Dinitrogen Tetraoxide

N2O4

Polyatomic Ionic Compounds (metal—nonmetal)

1. Copper (I) Sulfate____________________________________

2. Ammonium Acetate ______________________________________

3. Lead (II) Phosphate___________________________________

4. Ammonium Carbonate_______________________________________

5. Potassium Chlorate_________________________________________

6. Lithium Nitrate____________________________________________

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

Covalent Compounds (nonmetal—nonmetal)

1. Dichlorine Oxide___________________________________________

2. Chlorine Dioxide____________________________________________

3. Carbon Disulfide____________________________________________

4. Nitrogen Monoxide__________________________________________

5. Chlorine Tetroxide_________________________________________

6. Diphosphorus Pentoxide______________________________________

C4.2e: Given the formula for a simple hydrocarbon draw and name the isomers

Given the formula for a simple hydrocarbon, draw and name the isomers: Remember simple hydrocarbons are organic compounds consisting of only hydrogen and carbon. Recall that Alkanes are the simplest hydrocarbons. These compounds are named by using a prefix that tells the number of carbon atoms that are linked in the longest uninterrupted chain in the molecule. These names end with “ane”.

Isomers are compounds with the same molecular formula but different structural formula. For example:

Naming Structural Isomers: https://youtu.be/oUaXduj3xPM

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________Isomers: http://www.gcsescience.com/o22.htm

1. The number(s) at the front of the name tell us which C atom the branched carbon hangs off. This number is the lowest number possible, i.e. you can count in from either side!

2. The second word describes the branched carbon. In the example above, it is called methyl because the C

atom has one less H atom than methane (CH3). If there is more than one number at the beginning of the name, then methyl becomes 2, 2-dimethyl, 2, 3, 3-trimethyl etc.

3. The last part of the name is the longest unbroken chain. In the example above, the longest unbroken chain is 3 carbons (remember, you can count around corners). From the table above, we can see that 3 carbons mean it is called propane, so that is what it is called.

Practice Skill:

1. Draw and name 3 isomers of C5H12.

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________

2.

Which of the above are the correct structural formulas and names for the isomers of C5H12?

A. 1 & 3B. 1 & 4C. 3 & 4D. Neither one.

C4.6a, C4.6b: The Mole-given the mass of a compound or element you can calculate the number of moles or the number of individual particles.

https://youtu.be/F90KmCYjZBc https://youtu.be/zWzA-T54pPI https://youtu.be/09g6nN2PpVE

Example: Borax is the common name of sodium tetraborate, Na2B4O7. In 20 g of borax a) how many moles of boron are present and b) how many atoms of boron are present?

a)

2. Start with what you are given which is 20 g of Na2B4O7 and set up your factors to ensure that you end up with moles of Na2B4O7.

There are 0.099 moles of Na2B4O7 in 20g of Na2B4O7.

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________b) 1. Now calculate number of B atoms present in 20 g of Na2B4O7. Understand that there are 4 atoms of B in one formula unit of Na2B4O7. This means that in 1 mole of Na2B4O7 you have 4 moles of B.

You also need to know that in 1 mol of B you have 6.02 x 10 23 atoms of B.

And last you need to include the molar mass of Na2B4O7.

2. Now calculate the number of B atoms. Start with what you are given, the 20 g of Na2B4O7, and you need to go from grams to mols to number of atoms.

Practice Skill: Given the mass of an element or compound calculate the number of moles or the number of particles for that element or compound.Mass to moles: https://youtu.be/VAyGe_fW3FEMass to number of molecules: https://youtu.be/tBbCX6dQZPoMass to number of atoms: https://youtu.be/qKqg5AtNNzI

1. How many moles are contained in 40 g of Na?

2. How many moles are in 250 g of NaCl?

3. How many atoms of H are contained in 15 g of H?

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Unit 5-Nomenclature and Formula Stoichiometry Name: ________________________________________4. How many atoms of N are in 0.5 g of N2 gas?

5. How many moles of glucose (C6H12O6) are contained in 165 grams of glucose?A. 1.90 molesB. 1.09 molesC. 0.916 molesD. 0.0917 moles

6. How many atoms are in a 12.0 g sample of lithium?A. 1.74 x 1023 atomsB. 6.02 x 1023 atomsC. 1.04 x 1024 atoms

D. 7.24 x 1024 atoms

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