Fall Chemistry Exam Study Guide St. Albans School

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Chemistry Study guide
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Chapter II
Chemistry is the Study of matter
● Matter has the properties of Volume and Mass
● Mass is volume
● Volume Takes up space
Ways to Classify Matter
Solids
● Molecules are compact, little vibrations, very organized and have a set volume
Liquids
● Takes the shape of the container which means there is no set shape. Molecules are just as
compact as solid molecules and in some cases, even more compact (h20).
● not organized, and a lot of vibrations
Gases
● No set shape and volume of a gas CAN change
Mixtures
● A combination of two or more pure substances
● are not chemically bonded
● Retains their original properties
● Can be combined in any ratio
Ways to Separate Mixtures
●
●
●
●
●
Filtration (uses particle size)
Distillation (uses boiling points)
Chromatography (based on difference in polarities)
Centrifuging (using difference in density)
Magnetism (using magnetism to separate)(only Cobalt, iron, and manganese are
magnetic)
Pure Substances:
● Are elements and compounds with their own unique Physical and Chemical properties
Physical:
● Soluble
● Boiling point
● color
● freezing point
● density
● magnetism
● PH
● malleable
Chemical
● Flammability
● Smell
● Does it react w/ acid? w/ water?
Chapter III
● Back in the Day, they called chemist alchemist
Elements
● Each element of the same type has the same number of protons. the atomic number is the
number of protons
Metals
● They conduct electricity
● They are malleable (able to be bent into any state)
● They conduct heat
● They are ductile (able to be bent into wires)
● Most of them are lustrous (shiny)
Non-Metals
● Cannot conduct electricity
● they’re are not ductile
● Not malleable
● Doesn’t conduct heat
Metalloid
● Semiconductor (used in computers)
● Si - Silicon
Chemical symbols for major elements
H=hydrogen Ar=Argon
Li=lithium
Kr=Krypton
Na=sodium
Xe=Xenon
K=potassium Al=Aluminum
Be=Beryllium
Pb=Lead
Mg=Magnesium Si=Silicon
Ca=Calcium
P=Phosphorus
Sr=Strontium
S=Sulfur
Ba=Barium
Cl=Chlorine
Mn=Manganese Br=Bromine
Fe=Iron
Se=Selenium
Ni=Nickel
Rb=Rubidium
Cu=Copper
I=Iodine
Zn=Zinc
Ag=silver
Au=gold
Hg=Mercury
B=boron
C=carbon
N=nitrogen
O=oxygen
F=Fluorine
Ne=Neon
He=Helium
History
Democritus (400 B.C. -300 B.C.)
● First to theorize that all matter compose of atoms
● Atoms come means indivisible
● Not based on scientific evidence
John Dalton (1803)
● English school teacher first to prove existence of atoms
● Theorized that atoms are (*= true)
○ Tiny*
○ Indivisible
○ unchanged in chemical reaction
○ no subatomic particles
○ uniformly dense
JJ Thomson (1890)
● Determined that atoms are composed of + and - stuff
● Created the plum pudding model
● Proved his theory based on cathode ray experiment
Ernst Rutherford
● Created the gold foil experiment
● Polonium gives off a charged particle called an Alpha particle
● In the experiment, he show alpha particles at gold foil
○ 99.9% made it through
○ 0.09% deflected to the side
○ 0.01% bounced back
● His experiment that in the center of every atom was a small, dense, positively charged
object
● Here is a video which describes the experiment:
http://www.youtube.com/watch?v=5pZj0u_XMbc
Law of Constant Composition
● “The same compound is always composed of the same elements in the same ratio”
Subatomic
particles
Charge
Relative
charge
mass
Relative mass location
Electrons
-1.6x10-19
-1
9.11x10-31
0 amu
surrounds the
coulombs
atom
Protons
1.6x10-19
coulombs
+1
1.67x10-27
1 amu
nucleus
Neutrons
0
0
1.67x10-27
1 amu
nucleus
Nuclear Symbol Notation
12
6
C
● The number on the top is the Mass number, and the number on the bottom is the Atomic
number
Example 1:
12
C= 6 protons, 6 neutrons
13
C=6 protons, 7 neutrons
14
C= 6 protons, 8 neutrons
Hyphen notation
Carbon-12
● 12 is the mass number
● that means it has a mass number of 12, which means it has 6 protons and 6 neutrons
Uranium
● 99% of uranium is uranium 238
● The rare form (the form used in bombs) is uranium 235. AKA enriched uranium
Compounds
Compound:
● A combinations of two or more elements which are
1. Chemically bonded
2. have unique physical and chemical properties, different from their elements
3. Can only be combined in a whole number ratio
Types of Compounds
● Covalent
○ Consist of two non metals
● Ionics
○ Consist of one metal and a nonmetal
Chapter IV: Nomenclature
Rules of Covalent nomenclatures
1. Always put the more metallic element first
2. Use greek prefixes to indicate ratio of atom
a. 1: Mono 6: Hexa
b. 2: Di
7: Hepta
c. 3: Tri
8: Octa
d. 4: Tetra
9: nona
e. 5: Penta 10: Deca
3. Drop last syllable for the second element. add “ide”
4. Drop starting mono on second element
5. Don’t reduce subscript
Ionic Compounds
Ions
● Ions with a positive or negative charge
○ Gains or loses an electron
Cations
● Atoms with a positive charge, formed from losing and electron
Anions
● atoms with a negative charge, formed from gaining and electron
Ionic nomenclature
1. Write the metal first
2. use charges to determine the ratio of cations to anions
a. NO greek prefixes
3. add “ide” to the last element
4. Reduce subscript (only IONIC)
5. Ionic compounds must have a neutral charge
Metals with more than 1 charge
● Metals always have a positive charge
○ use roman numerals to indicate charge
● Ionic compounds with more than two elements are called polyatomic ions
Chapter V: Measurements and Calc.
1. Scientific Notation
2. Metric unit
3. Uncertainty measurement
4. Density
6. Best fit line
7. Dimensional analysis
Scientific notation
● Useful for very big or small numbers
● Based on power 10
● Speed of Light = 3.00 x 10^8
● Charge of an electron = -1.60 x 10^-19
● Radius of a hydrogen atom = 5.29 x10^-11
● Mass of the earth is 5.98x1024
Metric system
● Length (meters)
● Mass (grams)
● Temperature (celsius)
● Time (seconds)
● Brightness (lumen)
● Quantity (mol)
● Charge (coulombs)
Uncertainty in Measurement
● No scientific instrument can give a perfect measurement, therefore, the last
numbers recorded when collecting data are an estimate
Significant Figures
● A scientific method for rounding numbers ; rules to determine if a number is
“significant”
○ All non zero integers are significant
■ 234 3 sf
■ 26,754 5 sf
○ Leading zeros are never significant
■ 00254 3 sf
■ 0674.2 4 sf
○ Captive zeroes are always significant
■ 101 3 sf
■ 50202 5 sf
○ Trailing zeroes are significant if there is a decimal point anywhere in the
number
■ 1.00 3 sf
■ 100 1 sf
■ 10.00 4 sf.
● A calculator cannot be better that its worst measurement
● Density = Mass/Volume
○ ex: 452.0/ 350 = 1.291428571 = [1.3 g/ml]
● A number calculated by addition or subtraction cannot have more decimal places
than the measurement with the least numbers of decimal places
○ ex: 24.367g + 120.23g + 1.1112g = 145.7082g = [145.71]
○ ex: 273.15 + 25 = 298
○ ex: 297.1 k - 273.15 = 23.95 = [24.0]
Chapter VI
Percentage Composition
● Percent = Part/Total x 100
Empirical vs Molecular
● H2O2 is the Molecular
HO is the Empirical
● N2O4 is the molecular
NO2 is the Empirical
● P3O9 is the Molecular
PO3 is the Empirical
● C6H12O6 is the molecular
H2O is the Empirical
● H2O is the molecular
H2O is the Enpirical
How to Find the Empirical Formula
1. Divide the Molar Mass of the Molecular Formula (given) = Whole Number
Molar Mass of the Empirical formula(given)
2. Multiply the whole number by the subscripts
Empirical Formula Problem
● A mineral is found to 50% g Sulfur and 50.0 g Oxygen. What is the empirical
formula of this compound?
○ 50.0 x 1molS = 1.5576 mol S = 1 , 50.0 x 1mol O = 3.125 molO =2.006
1
32.1 gS 1.5576 mol S
1
16.0 gO 1.5576
=[SO2]
Mole
● A mole is 6.02x1023
● used to measure atoms
Chapter VII
Law of Conservation of Mass(Matter)
● Matter cannot be created or destroyed (except in a nuclear reaction)
● The mass of substances produced (products) by a chemical reaction is always
equal to the mass of the reacting substances
4 Signs of Chemical Change
● Produce a gas
● Color change
● Formation of precipitate (solid formed from mixing solids)
● Change in energy
5 Types of Chemical Reactions
● Synthesis
○ Mg+O2 -> MgO
● Decomposition
○ CO2 -> C + O2
● Single Displacement
○ AB+C -> AC +B
■ Only occurs if the lone element is more reactive than the bonded
one. It will be shown on the activity series
● Double Displacement
○ AB+CD -> AD + CB
■ Metals always first
● Combustion reaction
○ C6H12O6+O2 -> CO2 + H2O
■ All combustions reactions have Carbon and Hydrogen in different
ratios
Chapter VIII
Solutions
A Solution is..:
● Homogenous mixture. A mixture in which the individual component cannot be
distinguished
Solute:
● The substance in lesser amounts in a solution
Solvent:
● The substance in the greatest amount in a solution
The universal solvent is water
The Three types of Electrolyte solutions
1. Strong electrolytes
a. Great conductor of energy
i.
This is because they dissociate completely in water.
ii.
Dissociate: break up into their ions completely
b. All soluble compounds, Strong acids are STRONG electrolytes
● Strong Acids
○ Hyrdrochloric acid: HCL
○ Hydrobromic Acid: HBr
○ Hydroiodic Acid: HI
○ Nitric Acid: HNO3
○ Sulfuric Acid: H2SO4
Practice Test
Section 1: Multiple choice
1. Which one of the following option is not a way to separate mixtures
A. Distillation
B. Concentration
C. Chromatography
D. Magnetism
2. An example of a chemical property is
A. Smell
B. density
C. Boiling point
D. Soluabilituy
3. Mixtures are ____
A. Chemically bonded
B. Only combined in one ratio
C. Created of 3 or more pure substances
D. All of the above
4. Democritus created which theory
A. Matter is composed of atoms
B. Atoms have positive and negative charges
C. Atoms contain a nucleus
D. Matter can be broken down completely
5. John Dalton correctley theorized that
A. Atoms or tiny
B. indivisible
C. uniformly dense
D. unchanged in chemical reactions
E. There are no sub-atomic particles
F. A and B
G. C and E
H. All of the above
6. The law of Constant composition proves that
A. Atoms cannot be broken down
B. compounds are made of the same element in the same ratio
C. Elements create compounds
D. Compounds cannot be decomposed
7. Who created the plum pudding model?
A. J.J. Thomson
B. John Dalton
C. Ernest Rutherford
D. Democritus
8. Which of the following is NOT matter
A. Virus
B. Air
C. Light
D. Blood
9. Which one was discovered first?
A. Protons
B. electrons
C. Nuetrons
10. Which family is only solids
A. Halogen
B. transitions metals
C. nitrogen family
D. alkali earth metals
Fill in the blank
1.
Chris?
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