A Review of ChemistryEverything You Wish You’d Have

Studied Harder Last Year! Or

“Oh God, Not Again!” 

click on "Actions" button to download

States of Matter

• Solids-the particles in a solid are packed tightly together so there is little movement.o definite volume-definite shape.

• Liquids-particles in a liquid are much farther apart and can move around more. definite volume-indefinite shape.o definite volume-indefinite shape.

• Gases-particles very far apart expand to fill container.o indefinite volume-indefinite shape.

Changes in State

• When a substance goes from one state to another.

• SolidLiquid=melting (for H2O-32oF or 0oC)

• Liquidgas=evaporating (for H2O-212oF or 100oC)

• Gas liquid=condensing (for H2O-212oF or 100oC)

• LiquidSolid=freezing (for H2O-32oF or 0oC)

Pure Substances and MixturesMatter

Pure Substance Mixture

Element Compound Homogeneous Heterogeneous

A pure substances has a definite and constant composition. Pure substances can be elements like Gold or Potassium or compounds like salt or sugar. Elements are made of only 1 kind of atom. They cannot be taken apart.Compounds are made of 2 or more different kinds of atoms. They can be chemically taken apart.

A mixture is a combination of pure substances. The composition may vary. Mixtures can be taken apart by filtration, distillation, evaporation etc.Homogeneous mixture is one that looks the same throughout like Koolaid.Heterogeneous mixture is one that is different throughout like a granola bar.

Measuring Matter

• The SI systemo Decimal system with basic units for mass,

length, and volume and prefixes that modify them.

Units Prefixes Mass=gram kilo (k) 1000 Length=meter centi (c) .01 Volume=liter milli (m) .001

Converting SI Units

Dimensional Analysis:SI/English Units

• Unit factors may be made from any two terms that describe the same or equivalent "amounts" of what we are interested in. For example, we know that

• 1 inch = 2.54 centimetersWe can make two unit factors from this information:

Properties of Matter

• Chemical Properties -describe a substances ability to change into something else. o Flammabilityo Reactivity

• Physical Properties -describe a substances physical characteristics.o Masso Coloro Density

Physical Properties

• Extensive property-depends on how much matter is present. Mass and volume are extensive properties.

• Intensive properties-do not depend on amount of matter; a small chunk of gold is just as yellow as a large chunk of gold.

Density d=m/v Density=mass */* by volume Unit is g/cm3

Measuring Density Irregular solid Water displacement

Regular solid find mass, find volume divide

Temperature Scales

Converting Temperature from scale to scale

• K=oC + 273• oC=5/9 (oF-32)• oF=9/5 (oC) + 32

• What is normal body temperature 98.6oF in oC?

• Answer 37oC

Subatomic Particles

• Three major particleso Proton Eugen Goldstein cathode ray tube

+charge 1 amu (mass) Located in nucleus

o Neutron James Chadwick no charge 1 amu (mass) Located in nucleus

o Electron J J Thomson cathode ray tube -charge No recognizable charge Outside the nucleus

Dalton’s Atomic Theory

• 1. All elements are composed of tiny indivisible particles called atoms

• 2. Atoms of the same element are identical. The atoms of any one element are different from those of any other element

• 3. Atoms of different elements can physically mix together or can chemically combine in simple whole-number ratios to form compounds

• 4. Chemical reactions occur when atoms are separated, joined or rearranged. Atoms of one element are never changed into atoms of another element as the result of a chemical change

Two Changes to Dalton’s Theory

• 1. Atoms are not indivisible Rutherford’s Nuclear Modelo They have “stuff” inside

Nucleus Protons Neutrons Quarks Neutrinos

• 2. Atoms of one element can be changed to different element during a nuclear reaction.

The Nucleus

• 1911 Ernest Rutherford discovered the nucleus with the gold foil experiment.

• Very small!!! If Superdome in New Orleans represented an atom, the nucleus would be about the size of a pea on the 50 yard line.

• Holds protons and neutrons, thus most all of the mass of an atom.

Protons + Neutrons

• Sum of protons + neutrons = mass number.

• Number of protons =atomic number

Calculating Protons, Neutrons and Electrons

• Uranium’s atomic number is 92 (# or protons)

• Uranium’s mass number is 238 (protons plus neutrons)

• To find # of neutrons in U, subtract the atomic # from the mass #.

• # neutrons =146• # of electrons = mass #

(In a neutral atom)

Electrons

• Electrons can be considered to orbit the nucleus in certain energy levels.

• The outermost electrons from the nucleus are called the valence electrons.

• Valence electrons are involved in bonding.

• Number of valence electrons also determine atoms reactivity.

Isotopes

• An isotope is an atom that has the same number of protons (or the same atomic number) but different number of neutrons (or different atomic mass).

Ions

• In neutral atoms, the number of electrons = the number of protons.

• Ions have a different number of electrons.• Some atoms gain electrons and some

lose electrons.• Atoms that gain e- become negatively

charged ions or anions.• Atoms that lose e- become positively

charged ions or cations.

The Periodic Table

• Mid-1800’s Dmitri Mendeleev noticed a repeating pattern of chemical properties in the elements that were known at the time.

• Mendeleev first arranged the elements in order of increasing atomic mass.

• Very similar to todays PT. • Note exceptions---Co-Ni, Te-O

Arrangement of the PT

• Elements arranged in increasing atomic number.• Horizontal rows 1-7 are periods.

o All elements in a period have electrons in same energy level.

• Vertical columns 1-18 are groups or families.o Members of families have same number of valence

electrons thus, similar properties• Metals left of staircase, nonmetals right of

staircase, metalloids touching the staircase.

Families or Groups

• Have similar properties• IA-Alkali Metals

o Li, Na, K, Rb, Cs, Fro Lose one electron in reactionso React violently in watero Commonly found in saltso Important in bodily chemistry

Families or Groups cont.

• IIA-Alkaline earth metalso Be, Mg, Ca, Sr, Ba, Rao Lose two electrons in reactions

• VIIA-Halogenso F, Cl, Br, Io Gain one electron

• VIIIA-Noble Gaseso He, Ne, Ar, Kr, Xe, Rno Very unreactive

A Groups

• Number in front of A Group Columns (1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A) corresponds to the number of valence electrons.o 1A-all have one valence e-o 2A-all have two valence e-o 7A-all have seven valence e-o 8A-have eight valence e--the magic number!

The octet makes the atom stable!

Periodic TrendsTrend Group Period

Atomic size

Ionization Energy

Ionic size

Electro-negativity

Shielding

Metals

• Solid (except for Hg, a liquid)• Shiny• Good conductors of electricity and heat• Ductile (can be drawn into thin wire)• Malleable (easily hammered into thin sheets)• Tend to lose electrons to become cations• Majority of elements are classified as metals

Nonmetals

• Brittle• Not malleable• Not ductile• Poor conductors of heat and electricity• Gain electrons to become anions• Some nonmetals are liquid

Metalloids: semimetals

• Partially conduct electricityo Semiconductorso Computer chips

Bonding:Ionic Bonds

• Ionic bonds are formed between a metal and a nonmetal.

• The metal wants to lose electrons and the nonmetal wants to gain electrons to achieve a stable octet of valence electrons.

• The transfer of electrons creates ions with opposite charges.

• Opposite charges attract each other.

The Octet Rule

• Atoms will gain, lose, or share electrons until there is a total of 8 valence electrons in their outer most energy level.

• 1A-have one too many, easier to lose 1 electron than gain 7.

• 7A-need only 1 more to have 8, easier to gain 1 than to lose 7.

Ionic charge

• You can often determine the ions charge by it’s position on the periodic table. All group 1A metals have a +1 charge.

• Group 2A metals have a +2 charge• Group 3A metals have a +3 charge.• Group 7A nonmetals have a -1 charge• Group 6A nonmetals have a -2charge• Group 5A nonmetals have a -3 charge

Transition metals

• Group/Family B- cannot determine charge by group #. Must memorize charges. o Fe+2, Fe+3

o Cu+1, Cu+2

o Mn+2, Mn+3

o Co+2, Co+3

o Sn+2, Sn+3

o Pb+2, Pb+4

Polyatomic Ions

• Ions aren’t always composed of only one kind of atom; sometimes they are polyatomic, composed of more than one kind of atom.

• Sulfate SO4-2 1 sulfur and 4 oxygen

• Nitrate NO3-1 1 nitrogen and 3 oxygen

• Chlorate ClO3-1 1 chlorine and 3 oxygen

• Phosphate PO4-3 1 phosphate and 4 oxygen

• Carbonate CO3-2 1 carbon and 3 oxygen

• Hydroxide OH-1 1 oxygen and 1 hydrogen

• Ammonium NH4+1 1 nitrogen and 4 hydrogne

Ionic Compounds

• When ionic compound is formed the cation and the anion attract each other-compound must be neutral!

• Writing ionic compound formulas Put metal and nonmetal side by side. Metal first!

Mg +2 Br-1

If charges add up to zero then just write the formula. If not, crisscross the charges to balance the formula. Charge on opposite ion become the subscript on other ion. MgBr2

Bonding:Covalent Bonds

• A covalent bond is a bond between two or more nonmetals.

• In a covalent bond, electrons are shared, not transferred. No ions!

• Same goal- octet of valence electrons.• Covalent compounds may share more

than one bond; two or three! (double or triple bond) more than one pair of electrons are shared

Covalent Bonding• Diatomic molecules

7 naturally occuring diatomic molecules• H2, N2, O2, F2, Cl2, Br2, I2

• Lewis Dot Structureso Valence electrons are represented as dots surrounding the atomic

symbol.

Exceptions to the Octet Rule

• NO2, PCl5, SF6, BF3

• The octet rule cannot be satisfied in molecules whose total number of valence electrons is an odd number.

VSEPR Theory

• Atoms in a compound will repel each other

• Because of this, atoms within a compound will situate themselves so that they are as far apart as possible.

Naming Covalent Bonds• Add prefix• Mono =1• Di=2• Tri=3• Tetra=4• Penta=5• Hexa=6• Hepta=7• Octa=8• Nona=9• Deca=10

Chemical Reactions

• Exothermico Gives off heat

• Endothermico Takes heat in

Types of Reactions

• Combination/Synthesis• Decomposition• Single Displacement• Double Displacement• Combustion

Balancing Reactions

• The Law of Conservation of Mass states that matter is neither created or destroyed in a chemical reaction. Thus you must have the same amout of stuff in your product as in the reactant.

Mole Road Map

• The road map can be used a guideline to tell you how to use the mole in

• converting information.• **Just decide what you are starting with and what

you want to figure out. Then find• those two points on the map above and follow

the roads.• **The roads represent the steps you will have to

do and the conversion factors you will• need to know in order to accomplish what you

want.

Molar Mass

• Add the atomic masses of all atoms in a compound

• NH3

• H2SO4

• CaCl2

%Composition

• Part/Whole x 100• KCl

• NaF

Molarity

• What is the concentration of the solution?• M=m/L

Dilutions

• M1V1=M2V2

Acid/Base

• Acid• Ph of less than 7• Have H+in the front of the formula• Strong acids decompose completely in water• Bases• Ph of greater than 7• Usually contain OH-• Strong bases decompose completely in water

Gas Laws

• 4 Important physical properties of gaseso Volumeo Pressureo Temperatureo Amount-moles

Boyles Law

• Pressure-Volume relationship if temp and amount stays the same

• P1V1=P2V2

Charles Law

• Temp-volume relationship if amount and pressure are kept the same

• V1/T1=V2/T2

Gay-Lussac’s Law

• Pressure-temp relationship when amount and volume are kept same

• P1/T1=P2/T2

Combined Gas Law

• When the properties cannot be held constant.

• P1V1/T1=P2V2/T2

Stoichiometry:How much needed? How much made?

• Mole Ratio