Chemical Symbols - Each element has a one, two or three letter symbol to represent it

- Symbols with more than one letter are always written capital letter then lower case letter

Diatomic molecules - elements found only combined covalently in nature

H2, N2, O2, F2, Cl2, Br2, I2

- Based on IUPAC system of naming

Element vs. Compound

Element

Cannot be chemically broken down into two different substances.

- Atoms of all the same type

Compound Combination of elements

a. All sample of a compound have the same properties

c. All areas of a compound are the same

Na Cu

NaCl CuSO4

b. Atoms in a compound are in a simple ratio

What’s in a Quarter?

What two elements do you think are found in a quarter? (Write the name an symbol below.

What do you think will happen when the RED HOT quarter is placed into the beaker of methanol?

Describe what did happen?

Is the reaction that took place exo or endothermic/

Why did the quarter change color?

Chemical formulas tell us two thingsType of elements present

Number of atoms

Examples

MgBr2

Al2O3

Ca(OH)2

1 Mg for every 2 bromines

2 aluminums for every 3 oxygens

1 calcium , 2 hydrogens and 2 oxygens

2 sets of OH

Example - How many sulfur atoms are present in Pb(SO4)2?2

How many oxygen atoms are present? 4 x 2 = 8

Subscript- Indicates number of atoms

Coefficients -numbers placed in front of a chemical formula to indicate how many molecules are present

Ex.

6 MgS

MgSMgSMgSMgSMgS

MgS

Burning Money!!!!

2 C3H7OH(l) + 9 O2(g) → 6 CO2(g) + 8 H2O(g) ∆Hrxn = -1987 kJ/mol

Examine the following equation and answer the questions that follow

What is the total number of molecules in this equation?

How many atoms of oxygen are in the equation?

Describe the reaction as either exothermic or endothermic.

Hydrates - Water gets trapped in the crystal structure of some ionic compounds

-The same amount of water is found in the crystal all the time

Ex. CuSO4* 5H2O

* Does not mean multiply!!! It means it is an hydrate!

Types of Chemical Formulas

Empirical Formula

Shows the simplest ratio of atoms

Examples

Molecular FormulaTells us how many atoms of each element are needed to form the molecule

C2H6

Sometimes the empirical formula and the molecular formula are the same CO2 H2O

-ethane - 2 C : 6H

C2H6

Molecular

C3H6

CH3

CH2

Empirical

Which of the following are empirical formulas?

A. H2O2 B. CO C. P2O4 D. Al2O3

What is the empirical formula of the following?

C6H12O6 Hg2O4 PbSO4

CH2O HgO2PbSO4

Writing Chemical Formulas

When Ba is combined with Cl, is the formula BaCl?

Or ClBa? Or Cl2Ba? Or Ba2Cl?

Based on OXIDATION NUMBERS

Oxidation number

Positive oxidation numberAtom loses partial or total control of electrons

Negative oxidation numberAtom gains partial or total control of electrons

Oxidation numbers -Indicate the number of electrons lost or gained in a bond

Written first

Written second

Mg BrCl CaO CuLi S

1. The element or ion with the positive oxidation state (the metal) is written first

+2 -1 Mg Br

-1 +2 Ca Cl-2 +? Cu O+1 -2 Li S

Write in the oxidation states, then write out who comes first.

2. The oxidation states of all elements in a compound must add up to zero

-For every electron lost, it must be gained by another atom-For every electron lost, it must be gained by another atomExample

Ca Cl+2

Loses control of 2 e-

-1

Gains control of 1e-

Add one more Cl-1 to get to zero

Cl-1

2 e-

CaCl2

H O

Li S

+1 -2 H2O

+1 -2 Li2S

3. Polyatomic ions are treated as one element

Ca SO4

Na PO4

+2 -2CaSO4

+1 -3 Na3PO4

4. If a polyatomic ion is used more than once, put parentheses around it

Ca OH

NH4 SO3

+2 -1 Ca(OH)2

+1 -2 (NH4)2SO3

Practice

Lithium oxide

Magnesium iodide

potassium phosphate

ammonium nitrate

aluminum oxide

calcium phosphate

Li+1 O-2 Li2O

Mg+2 I- MgI2

PO4-3K+1 K3PO4

NH4+ NO3

- NH4NO3

Al+3 O-2 Al2O3

Ca+2 PO4-3 Ca3(PO4)2

Nomenclature Naming compounds

1. Binary Compound Consists of 2 different elements

To name these, use the name of the first atom, remove “ine” from the second atom and add “IDE”

NaCl Na__________ Cl_________

NaCl _____________________

You must know the –ide names for the following

Hydrogen

Oxygen

Bromine

Iodine

Fluorine

Nitrogen

Selenium

Sulfur

Hydride

Oxide

Bromide

Iodide

Flouride

Nitride

Selenide

Sulfide

Examples MgBr2 LiOSrO AlI3

NaF ZnS

Magnesium bromineMagnesium bromideStrontium oxygenStrontium oxide Sodium fluoride

Lithium oxideAluminum iodideZinc sulfide

2. Ternary compounds Compounds with 3 or more elements

-usually a metal with a POLYATOMIC ION

Polyatomic ion Group of atoms bonded together to obtainan overall charge

Has special properties unlike the individual atoms

Often acts as one atom

Found on Table E

O |O - P - O | O

-3

PO4-3 phosphate

Name the following polyatomic ionsSO3

-2 OH- CO3-2 NH4

+

sulfite hydroxide carbonate ammonium

Polyatomic ions bond IONICALLY with other ions

Naming compounds with polyatomic ions

- Do not change any parts, take the name of each part of the compound

-Circle the polyatomic ion in each compound, then name the compound

MgSO4 NaSCN

LiOH NH4OH

CaCO3 Li2SO3

Al(OH)3

Magnesium sulfate

Lithium hydroxide

Calcium carbonate

Aluminum hydroxide

Sodium thiocyanate

Ammonium hydroxide

Lithium sulfite

Naming Covalent Compounds

-compounds with only nonmetals

-using Table S, write the name of the element with the lower electronegativity first

-use prefixes to tell how many of each element are present

Ex. CO2

2.6 3.4

Carbon dioxide

N2Cl2

3.0 3.2

Dinitrogen dichloride

2 oxygen's

Try: Carbon tetrachloride

Diphosphorous pentoxide

Name the following Compounds

LiBr

MgSO4

CaCO3

SrCrO4

ZnS

Al2(SO4)3

NH4NO3

Write the empirical formula

C2H2 PbCl4 H2O2C6H12O6 P2O4

Write out the following formulasCalcium oxide

Lithium Sulfide

Lithium Sulfate

Magnesium phosphate

Aluminum carbonate

Nitrogen dioxide

So far, we have learned how to take different elements and combine them together to make a compound.But there are some elements that have several oxidation states.

For example, what is the formula for lead oxide?Pb has two oxidation states Pb+2 and Pb +4

Pb+2 O-2

PbOPb+4 O-2

O-2

PbO2Which of the two is correct?

BOTH are correct!

How can we have two different formulas with the same name?We need a way to distinguish between these two.

- used when the first part of a compound (the positive one) has two or more positive oxidation states.

Which of the following requires the stock system?

CuO MgO LiNO3

NO CaSO4 Ni(NO3)2 ZnCO3

Yes NO

Yes YesNO

NO

NO

How is the stock system used?How is the stock system used?

1. Assign oxidation numbers to the elements in the compound

Pb+2 O-2

PbO

Pb+4 O-2

O-2

PbO2Pb is in the +2 state, so it is called

Lead (II) oxidePb is in the +4; state, so it is called

Lead (IV) oxide

SnCl2

The Cl must be in the -1 state, since Sn must be a positive oxidation state,

-1

Since there are two Cl’s, the Sn must be in the +2 oxidation state to cancel out the Cl’s

-2

+2Sn has an oxidation state of +2 or +4.

TinTin (II)(II) ChlorideChloride

+2 = 0

2. Write the oxidation state of first element as a roman numeral

Practice - All of the following compounds need the stock system. Determine the oxidation state of the cation (the first ion) and write out the name.

CuNO3

NiF2

HgO

Hg2O

FeCl3

NO2

-1+1Copper (I) nitrate

-1+2 Nickel (II) fluoride

-2+2-2+2

Mercury (II) oxide

-2+1 Mercury (I) oxide

-2+2

-1

-3

+3

+3

Iron (III) chloride

-2

-4

+4

+4Nitrogen (IV) oxide

If we are given a chemical name that uses the stock system, how do we write the formula?

Example - What is the chemical formula for Copper (II) oxide?

We know that the compound contains copper and oxygen

Cu O

And we know that oxygen must take a -2 oxidation state

-2

Don’t have to look up copper. The (II) tells us that it is in the +2 state

+2

What is the chemical formula for copper (II) oxide?

CuO

What is the formula for Nickel (III) sulfate?

Ni SO4

-2 According to chart E!+3

Ni2(SO4)3

Now write out the formulas for the following.

Nitrogen (II) chloride

Iron (III) oxide

Lead (IV) carbonate

Copper (I) sulfate

N+2 Cl-1 NCl2

Fe+3 O-2 Fe2O3

Pb+4 CO3-2 Pb(CO3)2

Cu+1 SO4-2 Cu2SO4

- Shows what happens during a chemical reaction

The chemicals involved

How many of each molecule

Energy used, phases

Reactants Substances that exist before the reaction takes place

Always found on the left, or facing away from the arrow

Products Substances that exist after a chemical reaction Always found on the right, or facing the arrow head

The reaction arrow is the “ “. It is always found in the middle of a chemical reaction and it divides up the reactants and the products

Examples - List the reactant and the products of the following reactions

a. 2 H2 + O2 2 H2O

b. HCl + NaOH H2O + NaCl

Reactants Products

2 H2 O2 2 H2O

HCl NaOH H2O NaCl

Balancing a chemical equation

How many carbon atoms are on each side of the equation?1

How many oxygens are on each side of the equation?Three on the reactants, but only 2 one the products side

Is this possible?No, something must happen to the other oxygenC=O O = OO

OOOO = ?

CO + O2 CO2

We need another CO for the other oxygen to attach to.

C=O O = OOOOO

O =

C=O

OO

OO

O =

So two molecules of CO combine with one molecule of O2

2 CO + O2 2 CO2

Now the equation is balanced because we have the same number and types of atoms on both sides

2 C 2 C4 O 4 O

Problem 1: Write the balanced equation for the reaction between aluminum sulfate and calcium chloride to produce aluminum chloride and a white precipitate of calcium sulfate.

Step 1: Write the word equationAluminum sulfate + Calcium chloride Aluminum chloride + Calcium Sulfate

Step 2: Replace the words with the correct formulas

Al2(SO4)3 CaCl2 AlCl3 CaSO4 + +

Step 3: Adjust coefficients to make the equation balance. Use trial and error until both sides have same number of each element.

Al2(SO4)3 + CaCl2 AlCl3 + CaSO4

This is a hit and miss procedure. Often you will need to change the coefficients several times in order to balance the equation correctly

Remember to only change the coefficients, not the molecular formula

Examples

a. ____ NH3 _____ N2 + ____ H2

b. ____ Li2SO4 + ____ Na ____ Na2SO4 + ____ Li

c. ____ HCl + ____ Mg ____MgCl2 + _____ H2

2

2 2

2

3

-Some pure elements must exist as DIATOMIC molecules

H Pure hydrogen gas is H2

N Pure nitrogen is N2

This occurs for the following elements

H, N, O, F, Cl, Br, I

Example - Balance the following equation

Nitrogen + oxygen nitrogen (II) oxide

N2 + O2 NO2

Showing Energy changes in Reactions

A. Reactions that require energy are endothermic

Ex. 2 H2O + energy 2 H2 + O2

B. Reactions that give off energy are exothermic

Ex. 2 H2 + O2 2 H2O + energy

Match-Making

The first matches were invented in 1827 by chemist John Walker. He determined that a wood splint tipped with antimony (II) sulfide, potassium chlorate, gum and starch could be ignited by striking it against a rough surface.

Write the formulas for the following compounds

Antimony (II) sulfide

Potassium chlorate

Describe the reaction that took place when Mr. Stone lite the mixture on fire.

Was the reaction exo or endothermic and explain why.Why safety matches?Combustible materials are

separated between match and striking surface

Balance the following equations

•_____ KNO3 + _____ Na2SO4 _____ K2SO4 + _____ NaNO3

•_____ H2 + _____ Cl2 _____ HCl

•_____ Li + _____ O2 _____ Li2O

•_____ HgO _____ Hg + _____ O2

•_____ AlBr3 + _____ Cl2 _____ AlCl3 + _____ Br2

•Nitrogen + oxygen nitrogen(IV) oxide

•Barium chloride + sodium sulfate barium sulfate + sodium chloride

•Magnesium + sulfuric acid magnesium sulfate + hydrogen gas

•Potassium + water potassium hydroxide + hydrogen gas

Aluminum + hydrochloric acid aluminum chloride + hydrogen gas

There are four basic types of chemical reactions

Observe the products and the reactants to determine the type of reaction.

A. SynthesisTwo or more compounds combine together to produce one compound

A + B --> AB

Examples

2 H2 + O2 --> 2 H2O

Mg + O2 --> MgO2 2

Ex.

Exothermic reaction of Calcium oxide and water

B. Decomposition

Single compound breaks down into 2 or more compounds

AB --> A + B Examples

2 H2O --> 2 H2 + O2

NaCl --> Na + Cl22 2

Element + Ionic Compound

C. Single Replacement

Element + Ionic Compound

X + AB A + XB

Ex. Zn + CuSO4 ZnSO4 + Cu

What does an elephant use to clean it’s teeth?

Elephant toothpaste

H2O2(aq) → H2O(g) + O2(g) + energy

Balance the equation below

We’ve talked of many types of reactions at this point. Use to types that we’ve talked about during this unit to describe the reaction above.

What if the name of the H2O2 (you’ll need to use table E)

D. Double Replacement

2 compounds in solution are mixed

A B C DA A A

ACCC AB + CD --> CB + AD

Watch the oxidation states when making new compounds!Watch the oxidation states when making new compounds!

C

NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)

AlI3 + NaOH Al(OH)3 + NaI3 3

Ex.

Synthesis reaction – fog machine

Synthsis pg 113

Pg 117 synthesis

Single and double replacement 123

Elephant toothpaste decomp

Unknown Reactants and Products

-since matter can NOT be created or destroyed, you must always have the same number of each type of element on each side of the equation

-if you have a balanced equation you should be able to figure out what the unknown product or reactant is

EX. H2SO4 + 2 NaOH Na2SO4 + WHAT?

BaCl2 + K2CO3 WHAT? + BaCO3

2 NaHCO3 Na2CO3 + H2O + WHAT?

Determining Missing Mass in an Equation

RULE: Total mass of reactants = total mass of products

If 103.0g of KClO3 are decomposed to form 62.7 g of KCl and O2 gas according to the equation

2 KClO3 2 KCl + 3 O2

How many grams of oxygen are formed?

Total mass of reactants = 103.0 g

Total mass of products = 103.0 g

103.0 = mass of O2 + 62.7 g KCl

103.0 – 62.7g KCl = mass of O2

How many grams of silver nitrate are needed to react with 156.2g sodium sulfide to produce 595.8 g silver sulfide and 340.0 g sodium nitrate?

1. Rewrite and balance the equation.

2. Substitute masses in and solve for missing mass