1. UNIT 8: Formulas and Equations

2. AIM# 1: How can we distinguish between quantitative and qualitative information?
Chemical Symbols: Each element has a unique one-, two-, or three- letter symbol
The first letter is always capitalized (Table S, PT)
Almost all symbols are written without a subscripts as monatomic
Diatomic Molecules: elements that exist in nature as two identical atoms covalently bonded into a diatomic molecule
Br2, I2, N2, Cl2, H2, O2, F2

3. Chemical Formulas: compounds are composed of elements chemically combined in fixed ratios
Formulas use chemical symbols and number to show both qualitative and quantitative information about a substance
Qualitative: information that relates to things that cannot be counted or measured-
What elements are in the compound
Quantitative: information that deals with things that can either be counted or measured
The number of atoms of each element in the compound (subscript or coefficient can give us this info)

4. Empirical: simplest ratio Molecular: actual ratio
Ionic formulas are always empirical formulas
Molecular: actual ratio
covalently bonded substances form molecules, in some cases the empirical represents both empirical and molecular –H2O-
In other cases molecular formula is a multiple of the empirical formula C6H12O6 – six times the empirical CH2O

5. AIM: How can we distinguish between quantitative and qualitative information?
Example: Determine the quantitative and qualitative information in the following examples:
CaCO3
Zn3(PO4)2

6. AIM # 2: How can we know what elements form a compound and in what proportions?
Atoms and compound are electrically neutral – equal numbers of negative (electrons) and positive (protons)
Ions
Cations are positive
Anions are negative
Polyatomic Ion: group of atoms covalently bonded together, possessing a charge
Table E

7. Forming a compound: By attraction of oppositely charged ions
Monatomic or polyatomic ions attract each other in a ratio that produce a neutral compound
Coefficients: written in front of a formula, applies to entire formula, multiply the coefficient and subscript to determine the number of each type of element

8. Hydrates are compounds that contain definite amounts of water molecules
Ex: BaCl2·2H2O – Barium chloride traps 2 water molecules

9. *** Remember compounds must be neutral ***
For many elements, the oxidation state is equal to the charge found in the top right corner of each element box
1:1
Na+ & Cl - yields NaCl
Mg2+ & S2- yields MgS
Not 1:1 – Mg2+ & Cl -
Write the charge of one ion as the subscript of the other without the sign (# only)
Thus MgCl2; that is 1 Mg with a 2+ & 2 Cl with 1- each yields (2+) + 2(1-) = 0

10. Examples: Write the formulas for the following:
a. Al+3 and Br –
b. Ba+2 and CO3 -2
c. Cu 2+ and CO3 -2
d. Pb +2 and Cl –
e. Pb +4 and CrO4 -2

11. AIM # 3: How can we name compounds?
Binary Ionic (Metal–positive & Nonmetal–negative)
1st element (metal) – retains its name
2nd element (nonmetal) – change ending to “ide”
Ex: KCl is Potassium chloride
Other Ionic (Contains Polyatomic Ions)
Same as Binary except all polyatomic ions retain their name
Examples:
KNO3 is __________________
NH4Cl is _____________________
NH4NO3 is___________________
Potassium nitrate
Ammonium chloride
ammonium nitrate

12. Examples: Write the names for the following formulas:
a. Mg(SO4)
b. Na(OH)
c. Ca(OH)2
d. Li3(PO4)
e. (NH4)Cl

13. Nitrogen monoxide Dinitrogen tetroxide Iron (II) chloride
Covalent (2 Nonmetals)
Need prefixes to tell reader how many of each
Exception – if only one 1st element, don’t use mono
Examples
NO is _____________________
N2O4 is _____________________
Stock System (multiple oxidation states)
Examples are Iron, Tin, Copper (mostly transition metals)
a Roman numeral proceeding the metal tells the reader the oxidation number
FeCl2 is _________________
FeCl3 is _________________
Nitrogen monoxide
Dinitrogen tetroxide
Iron (II) chloride
Iron (III) chloride

14. BINARY ACIDS: composed of H and one other elements (TABLE K)
Naming Acids
BINARY ACIDS: composed of H and one other elements (TABLE K)
Ex) HCl - hydrogen chloride
Name begins with hydro followed by the name of other element with modified ending – ic
Ex) HCl – hydrochloric acid

15. TERNARY ACIDS: Have polyatomic ions containing O – table E
1.Anion suffixes – ate and – ite usually replaced by –ic and – ous respectively
-ate to –ic
-ite to –ous
Examples) HNO3 -> NITRIC ACID
H2SO4 -> SULFURIC ACID

16. AIM # 4: What are the different parts of a chemical equation and how can we use this to demonstrate the law of conservation?
Reactant(s) yield Product(s)
Reactant are on the left of the arrow (yield sign) and products are to the right of the arrow
State of matter is indicated by the letter inside the parenthesis
Example: C (s) + O2 (g) → CO2 (g)
Identify the reactants and products in the equation above…….

17. Review of chemical reactions (we already know this!!)
Endothermic
Heat is required for a reaction to occur, thus, energy is found on the reactant side
Example: H2O (s) + energy → H2O (l)
Exothermic
Heat is produced in a reaction, thus energy is found on the product side
Example: H2O (g) → H2O (l) + energy

18. BALANCING The Law of Conservation of Mass & Charge must be upheld
Example:
__ H2 (g) + __ O2 (g) → __ H2O (g)
“T chart method”
Remember – It’s coefficient x subscript to find the # of atoms 2 1 2

19. Nothing can be created or destroyed – law of conservation of mass
Count up the atoms on both side and fill in any missing elements or compounds
Same thing for missing mass
Practice:
If 103.0g of potassium chlorate are decomposed to form 62.7g of potassium chloride and oxygen gas according to the equation
2KClO3  2KCl + 3O2 how many grams of oxygen are formed?

20. AIM: What are the different types of chemical reactions?
Synthesis
2 or more reactants form 1 product
A + B → AB
Decomposition
1 reactant breaks down into 2 or more products
AB → A + B
Single Replacement
1 element replaces another
A (element) + BX (compound) → B (element) + AX (compound)
Double Replacement
2 elements/polyatomic ions replace two others
AB (compound) + CD (compound) → AD (compound) + CB (compound)

21. AIM: How can we predict products of a chemical reactions?
Single Replacement Reactions:
If the individual metal is above the metal that is in the compound a reaction will occur
Double Replacement Reactions:
If a solid is formed (Table F)
If a gas is formed
If a molecular substance such as water is formed

22. Using TABLE F Soluble Insoluble NH4Cl  MgOH
Cross out the first element or compound
Look for second element or compound on Table F check to see if it is paired with an exception
Determine solubility
Ex)
NH4Cl 
MgOH
Soluble
Insoluble

23. TABLE F
AgNO3(aq) + NaCl(aq)  AgCl(_____) + NaNO3(____) s aq

24. AIM: How can we determine an unknown reactant, product, or mass in a chemical equations?
Nothing can be created or destroyed – law of conservation of mass
Count up the atoms on both side and fill in any missing elements or compounds
Same thing for missing mass