Chemistry Chapter 3

Stoichiometry: Elements and Compounds
Chapter 3

Multiple Choice

How many different elements are present in the following chemical formula: CO₂

• 1

• 2

• 3

• 4

Multiple Choice

How many different elements are present in the following chemical formula: CoSO₄

• 1

• 2

• 3

• 4

Multiple Choice

How many Hydrogen atoms are present in glucose: C₆H₁₂O₆

• 6

• 12

• 24

• 1

Multiple Choice

How many Oxygen atoms are present in H₂O?

• 1

• 2

• 3

• 4

Multiple Choice

How many Sulfur atoms are in Cr(SO₄)₃?

• 1

• 3

• 4

• 12

Multiple Choice

How many Oxygen atoms are in Cr(SO₄)₃?

• 1

• 3

• 4

• 12

Multiple Choice

How many Chromium atoms are in Cr(SO₄)₃?

• 1

• 3

• 4

• 12

Multiple Choice

How many molecules of H₂O are present in: 3H₂O

• 1

• 2

• 3

• 4

Multiple Choice

How many atoms of Hydrogen are present in: 3H₂O

• 9

• 2

• 3

• 6

Multiple Choice

How many atoms of Oxygen are present in: 3H₂O

• 9

• 2

• 3

• 6

What are molecules?

Smallest particles of a compound which possess a unique set of properties and are capable of independent existence.

Examples of Molecules

• H2O (water)

• C6H12O6 (glucose, a type of sugar)

• N2 (nitrogen)

• O3 (ozone)

• CO2 (carbon dioxide)

• NaCl (table salt)

Multiple Select

Which are examples of a molecule?

• CO₂

• Na

• N₂

• O

Multiple Choice

A formula with the lowest whole # ratio of elements in a compound is called

• Molecular Formula
• Chemical Formula
• Empirical Formula 
• Distance Formula

Multiple Choice

What is the empirical formula for N₂S₃?

• NS

• N₃S₂

• N₂S₃

• N₁S_1.5

Multiple Choice

What is the empirical formula for C₄H₆?

• CH

• CH₃

• C₂H₃

• C₄H₆

Multiple Choice

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

Naming Binary Molecular Compounds

Example: N2O
•

The first element is always named first using the
entire element name.
•

N is the symbol for nitrogen.

•

The second element is named using its root and the
suffix –ide.
•

O is the symbol for oxygen so the second word is oxide.

Naming Binary Molecular Compounds

Example: N2O (continued)
•

Prefixes are used to indicate the number of atoms
of each element that are present in the compound.
The table on the next slide lists the most common
prefixes used.
•

There are two atoms of nitrogen and one atom
of oxygen so the first word is dinitrogen and the
second word is monoxide.

Naming Binary Molecular Compounds

Multiple Choice

What is the name of the following compound?

MgBr₂

• magnesium bromide

• magnesium bromine

• magnesium dibromide

• bromine magnesium

Multiple Choice

What is the formula for tetraphosphorous decasulfide?

• PS₁₀

• P₁₀S₄

• P₄S₁₀

• P₆S₅

Multiple Choice

What is the name of N₂O?

• nitrogen oxide

• dinitrogen monoxide

• nitrogen monoxide

• dinitrogen oxide

Vocabulary

• Ion: an atom that has gained or lost electrons

• Cation: positively charged ion, LOSES electrons

• Anion: negatively charged ion, GAINS electrons

Oxidation number

• Oxidation number: a positive or negative number that indicates how many electrons have been lost, gained, or shared to become stable.

• For ionic compounds, the oxidation number is the same as the charge on the ion.

• Example: A sodium ion has a charge of +1 and an oxidation number of +1

Multiple Choice

In ionic compounds, the oxidation number is ______ as the charge of the ion.

• the same

• different

Multiple Choice

What is the oxidation number of sodium (Na)?

• +1

• -1

• -6

• +6

Oxidation Numbers and the Periodic Table

• Elements in the same group (column) have the same oxidation number.

Multiple Choice

Elements in the same group have the same oxidation number.

• True

• False

Multiple Choice

Elements in group 2 (2A) have what oxidation number?

• +2

• +1

• -2

• -3

Naming Ionic Compounds (LiBr)

• Lithium (cation) / Bromine (anion)

• Lithium

• Bromide

• Lithium bromide

Open Ended

What is the name for Al₂O₃?

A. Oxidation Numbers

Multiple Choice

What are oxidation numbers?

• Number of electrons in the outer most energy level

• Number of protons

• Electrons gained or lost in chemical bonding

• Number of neutrons gained or lost

B. Ionic Names

1. Write the names of both elements, cation first. (the metal is the cation)

2. Change the anion’s (nonmetals) ending to -ide.

3. For ions with variable oxidation #’s, write the ox. # in parentheses using Roman numerals. Overall charge = 0.

B. Ionic Names Practice

• NaBr

• CrN

• FeCl₃

• Be₃N₂

• K₃P

• CrO

• BeO

• Mn₂O₇

• AlN

• MgCl₂

B. Ionic Names Practice

• NaBr

  • sodium bromide

• CrN

  • chromium (III) nitride

• FeCl₃

  • iron (III) oxide

• Be₃N₂

  • beryllium nitride

• K₃P

  • potassium phosphide

• CrO

  • chromium (II) oxide

• BeO

  • Beryllium oxide

• Mn₂O₇

  • manganese (VII) oxide

• AlN

  • aluminum nitride

• MgCl₂

  • magnesium chloride

Multiple Choice

Which of these combinations is an ionic compound made of?

• Metal and Metal

• Nonmetal and Nonmetal

• Metal and Nonmetal

• Cation and Cation

B. Ionic Formulas

1. Write each element symbol.  Put the cation first. (metal)

2. Look up the oxidation numbers for each element and write it as a superscript.

3. Overall charge must equal zero.

   1. If charges cancel, just write the symbols.

   2. If not, crisscross the charges to find subscripts.

4. Roman numerals indicate the oxidation #.

B. Ionic Formulas

1. Example: What is the formula for the compound that forms between magnesium phosphide?

​Mg²⁺ P^3-

^Mg₃^P₂

​3(+2)  +  2(-3) = 0

B. Ionic Formulas (practice)

• potassium chloride

  • K⁺  Cl^-     Þ  KCl

• magnesium nitride

  • Mg⁺²  N^-3     Þ  Mg₃N₂

• copper(II) chloride

  • Cu²⁺  Cl^-  Þ  CuCl₂

B. Ionic Formulas (practice)

• potassium chloride

  • K⁺  Cl^-     Þ  KCl

• magnesium nitride

  • Mg⁺²  N^-3     Þ  Mg₃N₂

• copper(II) chloride

  • Cu²⁺  Cl^-  Þ  CuCl₂

B. Ionic Formulas (Practice)

• Aluminum chloride

• lithium nitride

• magnesium iodide

• copper (II) sulfide

• iron (III) oxide

• Calcium oxide

• sodium sulfide

• chromium (VI) sulfide

• manganese (IV) oxide

• cobalt (III) fluoride

B. Ionic Formulas (Practice)

• Aluminum chloride

  • AlCl₃

• lithium nitride

  • Li₃N

• magnesium iodide

  • MgI₂

• copper (II) sulfide

  • CuS

• iron (III) oxide

  • Fe₂O₃

• Calcium oxide

  • CaO

• sodium sulfide

  • Na₂S

• chromium (VI) sulfide

  • Cr₂S₆ = CrS₃

• manganese (IV) oxide

  • Mn₂O₄ = MnO₂

• cobalt (III) fluoride

  • CoF₃

Multiple Choice

Li⁺ and P^3- create...

• Li₃P

• LiP₃

• LiP

• Li₂P

Multiple Choice

What is the charge of Cobalt (III)

• 3+

• 2+

• 8+

• 3-

Multiple Choice

What is the charge and symbol for Lead(IV)

• Pb⁴⁺

• Ld⁴⁺

• Pb^4-

• Ld^4-

Multiple Choice

Transition metals have multiple valence states. Which of the following is the correct way to represent Fe²⁺?

• Fe 2

• Fe II

• Fe (II)

• Fe (III(

Multiple Choice

What is the formula for Magnesium chloride?

• MgCl

• Mg₂Cl

• MgCl₂

• Mg₂Cl₃

Multiple Choice

What is the correct formula for the compound, lithium oxide?

• LiO

• Li₂O

• LiO₂

• Li₂O₂

Multiple Choice

What is the formula for manganese(III) oxide?

• MgO

• Mg₂O₃

• MnO

• Mn₂O₃

Multiple Choice

How do the following two elements bond together?
K¹⁺  S^2- 

• KS

• K₈S

• K₆S₃

• K₂S

​Moles

-a​n amount of a substance equal to a quantity of 6.02 x 10²³

​

-Avogadro's number (6.02 x 10²³)​

​

​Molar mass is atomic mass or the formula or molecular mass of a substance express in grams.

Find the formula/molecular mass of each substance? Write your answer in your notes?​

​

What did you notice with mole each substance compared to the formula, molecular, and the molar mass of each?​

​

Multiple Choice

What are AMU's

• Atomic Mass University

• Atomic Mass Units

• Atoms mean unity

• All Mass United

Multiple Choice

What are AMU's

• The unit used to measure the mass of atoms and molecules. Equal to 1/12 the mass of Carbon-12

• Unit to measure the radius of an atom

• Equal to a gram

• The unit used to measure large quantities of atoms

Counting Atoms

Multiple Choice

In 2 Au(NO3)3 how many oxygen atoms do we have?

• 6

• 3

• 18

• 12

Open Ended

Tell me: How do you think we will find the mass of a chemical compound?

Molar Mass

• The molar mass, also known as molecular weight, is the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule.

• Measured in the unit: grams/mole

How to Calculate Molar Mass

• 1. Count How many atoms you have of each element.

• 2. Find the atomic mass of each element and multiply it by their number of atoms.

• 3. Add up all the masses.

Example: Find the molar mass of Magnesium Nitrate Mg(NO₃)₂!

• Count Number of atoms.

• Find atomic mass from periodic table and multiply it by number of atoms.

• Add up all of the masses.

Example: Find the molar mass of Glucose C₆H₁₂O₆!

• Count Number of atoms.

• Find atomic mass from periodic table and multiply it by number of atoms.

• Add up all of the masses.

Multiple Choice

What is the Molar Mass for Calcium Hydroxide Ca(OH)₂?

• 74.1 g/mol

• 114.14 g/mol

• 58.09 g/mol

Multiple Choice

Find the Molar Mass for (NH₄)₂SO₄ Ammonium Sulfate!

• 132.16 g/mol

• 114.11 g/mol

• 118.15 g/mol

• 146.17 g/mol

Moles - Part 1

What is a mole and why do we need it?

Multiple Choice

Which would have more atoms?

• 1 mole of Li

• 1 mole of Au

• 1 mole of Si

• None, all are equal

Multiple Choice

How many particles are in a mole?

• 602

• 602 million

• 602 moles

• 6.02 x 10²³

Multiple Choice

What is the molar mass of AuCl₃?

• 96 g

• 130 g

• 232.5 g

• 303.3 g

Multiple Choice

Calculate the molar mass for Al(OH)₃

• 78.0 g/mol

• 72 g/mol

• 28 g/mol

• 25 g/mol

Multiple Choice

Calculate the molar mass for Al(OH)₃

• 78.0 g/mol

• 72 g/mol

• 28 g/mol

• 25 g/mol

Multiple Choice

What is the molar mass of CO₂?

• 12

• 16

• 32

• 44

Multiple Choice

What is the mass of one mole of aluminum?

• 27 g

• 13 g

• 54 g

• 14 g

Multiple Choice

The molar mass of an element is equal to its...

• Atomic mass

• Atomic number

• Oxidation number

• Valence electrons

Multiple Choice

Find the mass of 5.82 mol of MgCl₂. Round to the nearest tenth.

• 552.9 g

• 436.8 g

• 55.2 g

• 555.9 g

Multiple Choice

Find the mass of 5.82 mol of MgCl₂. Round to the nearest tenth.

• 552.9 g

• 436.8 g

• 55.2 g

• 555.9 g

Multiple Choice

How many moles are 2.85 x 10¹⁸ atoms of iron?

• 4.73 x 10^-6 moles

• 1.72 x 10⁴² moles

• 1.72 x 10^-42 moles

• 4.73 x 10⁶ moles

Multiple Choice

Which conversion factor should be used for the following question " How many molecules are there in 4.00 moles of glucose, C₆H₁₂O₆?

• 1 mole = 78.12 g

• 1 mole = 22.4 L

• 1 mol = 6.02x 10²³ particles

• more than one