1. Molecules, Compounds, and Chemistry Equations
Chapter 3
Than, K. Sugar Found In Space: A Sign of Life? Organic molecules found in gas swaddling a young star. National Geographic News. PUBLISHED August 30, 2012
Molecules, Compounds, and Chemistry Equations

3. Hydrogen, Oxygen, and Water
Hydrogen gas (____) is explosive
Oxygen gas (_____) is not explosive but must be present for combustion (fire) to occur
When these two gases come together to react, they form water
A molecule now with completely different properties!!!

4. Properties
The properties of compounds / molecules are generally different from those of the elements used to compose them
What “holds” these atoms together??

5. Chemical Bonds
Compounds are composed of atoms held together by chemical bonds
Chemical bonds are the result of interactions between charged particles
Electrons (-) and Protons (+) !!
Two MAIN types of bonds (more in the “bonding” chapters  ):
1. Ionic 2. Covalent

6. Chemical Bonds Two MAIN types of bonds
We have two whole chapters on chemical bonds (Chapter 9 AND chapter 10)
Ionic (a metal and nonmetal) – transferring of electrons – or stealing of electrons
Covalent (two nonmetals) – sharing electrons to obtain an octet and make everyone happy 

7. Image obtained from: http://kitkatyj. deviantart
Image obtained from: on October 17, 2016

8. Ionic Bonds Metals tend to lose electrons and form _____________
While nonmetals tend to gain electrons and form ______________
These oppositely charged ions are then attracted to one another by electrostatic forces
The results is an ionic compound
In the solid phase make up a lattice structure – a 3-D array of alternating cations and anions

9. Covalent Bonds
When two nonmetals bonds, neither actually give up or take on electrons, instead they share
facts-i-just-made-up.tumblr.com/post/ /sharing-is-caring-the-new-care-bears-series

10. Covalent Bonds
When two nonmetals bonds, neither actually give up or take on electrons, instead they share
The shared electrons interact with the nuclei of both atoms, lowering their potential energy through electrostatic interactions with the nuclei
Think of it like the (-) electron is holding together the two (+) nuclei

11. Chemical Formulas
Chemical formulas can be divided into three different types:
Empirical – gives the relative number of atoms of each element in a compound (like a ratio)
Molecular – gives the actual number of atoms of each element in compounds (not simplified)
Structural – shows lines between the elements to attempt to illustrate how they are organized or connected (bonded) together

12. Empirical Formulas
Empirical Formulas are just “simplified” down molecular formulas
Practice:
write out the empirical formula from each of the following molecular formulas
C4H8 B. B2H6 C. CCl4

13. Empirical Formulas
Empirical Formulas are just “simplified” down molecular formulas
Practice:
write out the empirical formula from each of the following molecular formulas
C4H8 A. CH2
B2H6 B. BH3
CCl4 C. CCl4

14. Empirical Formulas Empirical Formulas can also be calculated
To do this, you must have some information given to you
You must know a Percent Composition
So…. What is a percent comp?

15. Percent Composition (Mass Percent Composition)
A Percent Composition is the percentage by mass of each element in a compound.
Just like your grade on a test
First, calculate the molar mass of the ENTIRE compound (total points possible).
Then, divide that by the mass of the part you are trying to find the percent for (your score).

16. Practice with Percent Composition (Mass Percent Composition)
Calculate the percent composition of iron in iron(III)oxide.
Calculate the percent of Nitrate in magnesium nitrate.

17. Empirical Formulas
The Empirical Formula is a chemical formula that shows the composition of a compound in terms of the relative numbers and kinds of atoms in the SIMPLEST RATIO.
How do we find this simplest ratio?
You just did this using the easier way… what if we are not given a molecular formula but instead a percent composition of the compound?

18. Empirical Formulas
To calculate the empirical formula, you must first know the percent composition.
Using the percents, assume a 100g sample.
How will this help?
What units will this leave your percents in?

19. Empirical Formulas
Now that we are in grams of each component (from the percent compositions), we need to convert these to moles.
Last step, divide each number by the LOWEST number to determine what the lowest ratio values will be.

20. Lets Practice!!
Chemical analysis of a liquid shows that it is 60.0% C, 13.4% H, and 26.6% O by mass. Calculate the empirical formula of this substance.

21. More Practice!!
A dead alkaline battery is found to contain a compound of Mn and O. Its analysis gives 69.6% Mn and 30.4% O.
A compound is 38.77% Cl and 61.23% O.
A liquid compound is 18.0% C, 2.26% H, and 79.7% Cl.

22. Molecular Formulas
Molecular Formulas are multiples of Empirical Formulas.
A molecular formula is a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms.

23. Molar mass of the empirical formula
Molecular Formulas
The molar mass of a compound is equal to the molar mass of the empirical formula times a whole number, n.
Fill in the following table:
Empirical Formula
Molar mass of compound
Molar mass of the empirical formula
MM/EFM
Molecular Formula

24. Practice with Molecular Formulas
The empirical formula for a compound is P2O5. Its experimental molar mass is 284 g/mol. Determine the molecular formula of the compound.

25. Practice with Molecular Formulas
The empirical formula for a compound is P2O5. Its experimental molar mass is 284 g/mol. Determine the molecular formula of the compound.
Empirical Formula
Molar mass of compound
Molar mass of the empirical formula
MM/EFM
Molecular Formula

26. More Practice
A compound has an experimental molar mass of 78 g/mol. Its empirical formula is CH. What is its molecular formula?
A brown gas has the empirical formula NO2. Its experimental molar mass is 46 g/mol. What is its molecular formula?

27. Structural Formulas Yep that is it….
Mostly these are “organic” but can represent more than just these “hydrocarbons”

28. Atomic-Level View

29. Atomic-Level View
Atomic Elements are those that exist in nature with single atoms as their basic units
Examples: Gold, Helium, Iron, etc.
Molecular Elements do not normally exist in nature with single atoms, but instead as molecules or groups of atoms
Examples: O3, O2, S8, all your other ___________

30. Compounds
Molecular Compounds (molecules) are usually composed of two or more covalently bonded nonmetals
Examples: H2O, CO2
Ionic Compounds are composed of cations (metal) and anions (nonmetals)
Example: Na+ & Cl-  NaCl

31. Polyatomic Ions Look at the back of your Periodic Tables.
You know this list as “Polyatomic Ions”
Poly = many
Atomic = atoms
Ion = with a charge
Polyatomic Ions – an ion composed of two or more atoms with an overall net charge. Forms ionic (electrostatic) attractions / bonds

32. Practice
Classify each of the following substances as an atomic element, molecular element, molecular compounds, or ionic compound
Xenon
NiCl2
Bromine
NO2
NaNO2

33. More Practice
Classify each of the following substances as an atomic element, molecular element, molecular compounds, or ionic compound
Fluorine
N2O
Silver
K2O
F2O3

34. REVIEW: Ionic Compounds
Nomenclature Rules for “types A and B”
Ionic Compounds CAN have polyatomics!!
Name the same way
Type A (make the charges cancel and change the ending)
Type B (again, make the charge cancel and change the ending… use Roman numeral!)

35. REVIEW: Naming Molecular Compounds
This is Type C
Use prefixes
DO NOT use or even look at the charges
Will NOT use polyatomics!!!!!

36. Acids (not review!)
Acids are molecular compounds that release hydrogen ions (H+) when dissolved in water
The ‘acidic’ hydrogen is usually written out front (ex. HCl, HBr, HI, H2SO4, HNO3, HClO4)
HCl  (when dissolved)  H+(aq) + Cl-(aq)
Aqueous(aq) means ‘dissolved in water’

37. Acids
Acids are characterized by their sour taste and their ability to dissolve many metals
They are ___________ on the pH scale
pH actually is a measure of the H+ ion concentration

38. Naming Acids Binary Acids are composed of hydrogen and a nonmetal
Example: HCl(aq) = HYDRO + CHLOR + IC ACID
Try to Name: HF(aq), HI(aq), H2S(aq)

39. Naming Acids (oxyacids)
Oxyacids contain hydrogen and an oxyanion (an anion containing a nonmetal and oxygen – like nitrate or nitrite, sulfate or sulfite, etc.

40. Naming Acids (oxyacids)
Try naming: Write out:
HNO3(aq) Acetic Acid
H2SO3(aq) Benzoic Acid
HNO2(aq) Perchlorous Acid

41. Conversion Factors from Chemical Formulas
Think about CCl2F2
For every one mole of CCl2F2 , there are two moles of Cl
2 𝑚𝑜𝑙 𝐶𝑙 1 𝑚𝑜𝑙𝑒 CCl2F2
Let’s Practice  What would be the mass of Cl in 25.0 grams of CCl2F2?

43. Practice
What mass of hydrogen (in grams) is contained in 1.00 gallons of water? (the density of water is 1.00 g/mL)
3.785x103 grams H x102 grams H

44. More Practice
Determine the mass of oxygen in a 7.2 gram sample of aluminum sulfate

45. More Practice
Butane (C4H10) is used as a liquid fuel in lighters. How many grams of carbon are presented within a lighter containing 7.25 mL of butane? The density of liquid butane is g/mL)

46. Part 1: Describing Chemical Reactions

47. Chemical Reactions (rxns)
Chemical Reaction (rxn) – a process in which one or more substances are converted into one or more different substance
“bonds are broken, reformed, and gives you something new”

49. Some Vocab
Chemical Equations are used to “represent” or describe a chemical reaction (sometimes called “word equations”
Reactants –
Products –

50. Reactants MUST Come Together
You cannot hit a ball without touching it.
Reactions use the same concept
The reactants must come together and interact in order to react with one another
What happens with you:
Increase the concentration of the reactants?
Crush up the reactants?
Increase the temperature / pressure?

51. Word Equations Tell Us A Lot
Symbol
Meaning
(s), (ℓ), (g)
Substance in the solid, liquid, and gaseous state.
(aq)
Substance in aqueous solution (dissolved in water). 
“produces” or “yields,” indicating result or reaction
Reversible Rxn in which products can reform into reactants; final result is a mixture of products and reactants
Δ heat
 or 
Reactants are heated; temperature is not specified Pd
Name or chemical formula of a catalyst, added to speed a reaction.

52. Part 2: Balancing Chemical Reactions

53. Balancing Equations
The ________________ states that we cannot create or destroy matter / energy…
So, what we start with… we must end with!!
EXACTLY!!
Coefficients are used to ‘multiply’ substance quantities to make the number of moles the same on both sides of the ‘arrow’

55. Coefficients H2O represents water (2 H, 1 O)
2 H20 represents two moles of water (4 H, 2 O)
H202 represents hydrogen peroxide (2 H, 2 O)
A small change of the subscripts within the molecule will change the compound completely AND alter the entire reaction.

56. More on Coefficients
Determine the number of each atom in the following examples:
_1_Fe2O3 + _3_H2 
_3_ Ca(NO3)2 +
_1_ C6H12O6 + _6_ O2  _6_ H20 + _6_ CO2

57. Rules to consider when balancing
Identify reactants and products
If no equation is provided, identify the reactants and products and write an unbalanced equation for the reaction. (You may find it helpful to write a word equation first.)
If not all chemicals are described in the problem, try to predict the missing chemicals based on the type of reaction.

58. Rules to consider when balancing
Count atoms
Count the number of atoms of each element in the reactants and in the products, and record the results in a table.
Identify elements that appear in only one reactant and in only one product, and balance the atoms of those elements first. Delay the balancing of atoms (often hydrogen and oxygen) that appear in more that one reactant or product.
If a polyatomic ion appears on both sides of the equation, treat it as a single unit in you counts.

59. Rules to consider when balancing
Insert coefficients
Balance atoms one element at a time by inserting coefficients.
Count the atoms of each element frequently as you try different coefficients. Watch for elements whose atoms become unbalanced as a result of your work.
Try the odd-even technique (double the odd number) if you see an even number of a particular atom on one side of an equation and an odd number of that atom on the other side.

60. Rules to consider when balancing
Verify your results
Double-check to be sure that the numbers of atoms of each element are equal on both sides of the equation. Make sure your own work did not mess any “previously balanced” atoms.

61. Practice: Balance the following example:
Iron (III) oxide and hydrogen react to yield iron and water.

62. Practice: Balance the following examples: ___P4 + ___O2  ___P2O5
___C3H8 + ___O2  ___CO2 + ___H2O
Silicon reacts with carbon dioxide to form silicon carbide, SiC, and silicon dioxide

63. NEVER change subscripts to balance a reaction!!!

64. Part 3: Classifying Chemical Reactions

65. Reaction Types
There is an unlimited number of reactions that may occur in the real world.
To make learning them easier, we classify them according to what is taking place.
Five main types
Makes predicting products MUCH easier.

66. 1. Combustion Reactions Often used to generate energy.
Combustion Reaction – the oxidation of an organic compound, in which heat is released.
One reactant is a hydrocarbon and the other must be ______________.
Products are always carbon dioxide and water.

67. Combustion Reactions
Examples: ___C3H8 + ___O2  ___H2O + ___CO2 ___C2H5OH + ___  ___ + ___ Write down the combustion of CH4

68. 2. Synthesis Reaction (aka: combination reactions)
The word synthesis means “to put together”
Synthesis Reaction – a reaction in which two or more substances combine to form a new compound.
The reactants in many of these reactions are two elements or two small compounds.

69. Synthesis Reactions C + O2  CO2 2C + O2  2CO
CaO(s) + H2O(l)  Ca(OH)2(s)
Predict the products of the following synthesis rxns:
K + Cl2 
Mg + O2 

70. 3. Decomposition Reaction
Decomposition reactions are the opposite of synthesis reactions – they have only one reactant.
In a decomposition reaction, a single compound breaks down, often with the input of energy, into two or more elements or simpler compounds.

71. Decomposition Reactions
Water breaks down into its simpler components when introduced to electricity: 2H2O(l) > 2H2(g) + O2(g) Compounds made up of three or more elements usually do not decompose into those elements. CaCO3(s) > CaO(s) + CO2(g)
Electricity
Heat

72. Practice So Far:
Predict the product(s) and write a balanced equation for each of the following reactions:
The reaction of butane, C4H10, with oxygen.
The reaction of water and calcium oxide
The reaction of lithium with oxygen
The decomposition of carbonic acid.

73. 4. Single Displacement (replacement) Reactions
A single element reacts with a compound and displaces another element of the same charge from the compound.
Examples:
2Al(s) + 3CuCl2(aq)  2AlCl3(aq) + 3Cu(s)
Predict the following products:
CuSO4(aq) + Zn(s) 

74. Activity Series Used to make predictions about displacement reactions.
In the activity series, elements are arranged in order of activity with the most active on top.
In general, an element can displace those listed below it but not those above it.

75. What would you predict will happen when silver is put into a copper (II) nitrate soln.?

76. 5. Double Displacement (replacement) Reactions
Two compounds react with one another and swap cations / anions.
Examples:
HCl(aq) + NaOH(aq)  HOH(l) + NaCl(s)
Predict the following products:
Cu(NO3)2(aq) + Al2(SO4)3(s) 

77. Practice Classifying Reactions
Balance each of the equations below, and indicate the type of reaction for each equation
___Cl2(g) + ___NaBr(aq)  ___NaCl(aq) + ___Br2(l)
___CaO(s) + ___H2O  ___Ca(OH)2(aq)
___Ca(ClO3)2(s)  ___CaCl2(s) + ___O2(g)

78. Practice Classifying Reactions
Balance each of the equations below, and indicate the type of reaction for each equation
___C8H18(l) + ___O2(g)  ___CO2(g) + ___H2O(l)
__Zn(s) + __CuBr2(aq)  __ZnBr2(aq) + __Cu(s)
__AgNO3(aq) + __K2SO4(aq)  __Ag2SO4 + __KNO3(aq)

79. Practice With Activity Series
Predict whether a reaction would occur when the materials indicated are brought together. For each reaction that would occur, complete and balance the equation.
___Ag(s) + ___H2O(l)
___Mg(s) + ___Cu(NO3)2(aq)
___Al(s) + ___MgNO3(aq)

80. Predicting Products
Predict the products, write a balanced equation, and identify the type of reaction for each of the following reactions.
___H2SO4(aq) + ___KOH(aq)
___ C3H7OH + ___ O2 
___ Zn + ___ CuSO4 

81. Predicting Products
Predict the products, write a balanced equation, and identify the type of reaction for each of the following reactions.
___ BaCl2 + ___ Na2SO4 
___ Zn + ___ F2 
___ C5H10 + ___ O2 

82. Test Coming up!!
Continue Practicing!!!

83. Read on your own 
Read through Section 3.11: Organic Compounds (page ) – QUIZ!!
You need to know this section as well as naming this alkanes, alkenes, and alkynes
Know the skeletal notation, the vocabulary, and the functional groups from page Be able to ‘circle’ possible functional groups seen in a large drawn out organic molecule

84. Total Ionic Reactions
You can write out a chemical reaction illustrating EXACTLY what is taking place “in the pot”
Total Ionic Equations show us ALL the ions interacting in solution
Assign all phases – break apart “aqueous”
Some of these ions play an important role in the reaction, others just “spectate”

85. Practice
Write out the total ionic equations for the following reaction:
Sodium hydroxide reacts with sulfuric acid

86. Spectator Ions Spectators ions do not influence the reaction
They remain unchanged from the reactant side to the product side.
You may CROSS OUT and forget about spectator ions – they do not do anything
Think about your example reaction – cross out the spectator ions

87. Net Ionic Equations
After you cross out your spectator ions, you are left with a Net Ionic Equation, typically resulting in a “precipitate”
Net ionic equations are equations that show only the soluble, strong electrolytes reacting (these are represented as ions) and omit the spectator ions, which go through the reaction unchanged.
What are you left with from the NaOH + H2SO4 ?

88. So…. How do you know what is solid, liquid, or gas??
Use your best judgement !!!
How about aqueous???
There is a way!!

89. Solubility Rules

90. Practice
Silver nitrate reacts with potassium chloride Magnesium nitrate reacts with sodium carbonate

91. strontium bromide + potassium sulfate
manganese(II)chloride + ammonium carbonate
chromium(III)nitrate + iron(II)sulfate

92. End of Unit 3 