Chemistry and Organic Analysis Notes:
What is Chemistry?
- How one substance changes to another
- The _________ makeup of substances
Example: Water (the most abundant and important substances on earth) is made of 2
___________ atoms and 1 __________ atom.
Diagram of a H2O molecule:
Water has ________ degree angles between its hydrogen atoms.
Fundamental Concept of Chemistry:
1.
Matter is composed of various types of ______.
2.
One substance changes to another by re-arranging the way the atoms are attached to each
other.
The Scientific Method:
This is a very important process in Chemistry.
3 major parts to Scientific Method:
1.
Making observations- observations may be qualitative or quantitative. Observing any
physical or chemical changes that occur.
Qualitative- observations that are made using descriptive words, not numbers.
Example: the sky is blue, water is a liquid, and the JVS is big.
Quantitative- are observations that are made using numbers, not descriptive words.
Example: the water is 100 degrees, The JVS has a floor space of 13 acres, Mr. Charles weighs
196 lbs.
2.
Formulating hypotheses. A hypothesis is a possible explanation for an observation.
Example: Tommorrow I will go out to dinner with the family, This weekend I will go scuba
diving.
3.
Experiment- test carried out to prove or disprove a hypothesis.
*****Measurements in Chemistry*****
S.I. System – Systeme International d’Unites
- International system of measurements agreed on by all scientists.
- Example:
Seven base units make up the S.I. system:
Table 1: S.I. Units
Basic Unit
Abbreviation
Second
s
Meter
m
Kilogram
kg
Kelvin
K
Mole
mol
Ampere
A
Candela
cd
Quantity measured
time
Distance/length
mass
Absolute temperature
Amount of substance
Electric current
Light Intensity
** Other S.I. units can be derived from a combination of the above S.I. units **
Table 2: Units derived from S.I.
Derived Unit
Newtons
Joule
Watts
Definition
Kg x m/s2
Kg x m2/s2
Kg x m2/s3
Table 3: Prefixes for units of Measurement.
Symbol
Prefix
p
pico
n
nano
μ
micro
m
milli
c
centi
k
Kilo
M
Mega
G
Giga
Quantity Measured
force
energy
Power
Is equal to
One trillionth
One billionth
One millionth
One thousandth
One hundredth
A thousand
A million
A billion
T
E
Tera
Exa
A trillion
quintillion
Accuracy- how close a measurement is to the accepted or “correct” value.
Example: how close you hit to the bulls-eye on a dartboard.
Precision- how consistent you are with you measurements.
Example: throwing 5 darts on a dartboard with all 5 hitting somewhere outside the bulls-eye but
grouped together.
Question: Which of these measurements are precise? Which of these are accurate?
Question: Is the graduated cylinder accurate?
Is the graduated cylinder precise?
Is the Buret precise?
Trial
1
2
3
4
5
Average
Volume shown by Graduated
Cylinder
25 ml
25 ml
25 ml
25 ml
25 ml
25 ml
Volume shown by the Buret
26.54 ml
26.51 ml
26.60 ml
26.49 ml
26.57 ml
26.54 ml
Uncertainty- In every measurement you have some degree of imprecision. The higher the degree of
uncertainty, the less precise and accurate the measurement.
Temperature
3 common temperature units:
1. Fahrenheit
2. Celsius
3. Kelvin
What actually does temperature measure?
The average molecular movement of atoms.
TO FIND
Fahrenheit
Celsius
Kelvin
Celsius






FROM
Celsius
Fahrenheit
Celsius
Kelvin
FORMULA
°F = (°C × 1.8) + 32
°C = (°F − 32) /1.8
K = °C + 273.15
°C = K − 273.15
Convert 34 degrees to Celsius
Covert 50 degrees Celsius to Fahrenheit
Convert 20 degrees Kelvin to Celsius
Convert 89 degrees Fahrenheit to Kelvin
Convert 112 degrees to Fahrenheit
Normal body temperature is 98.6 degrees Fahrenheit. Convert this to Celsius and
Kelvin.
What is 0 degrees Kelvin Called? What is the significance of this measurement?
Density- property of matter that tells a scientist the mass of a substance per unit ______ of the
substance.
EQUATION FOR DENSITY:
Density= Mass
Volume
Mass- a quantity used to measure the resistance to a change in ______ of an object
Volume- the amount of space occupied by a three-dimensional object or region of space, expressed in
_____ _____.
Example: Floating ice and water
**Pure water has a density of 1.0 g/cm3
**Any substances that have a density ____ than 1.0 g/cm3 will ________ on water.
Which is denser, salt water or fresh water?
Why?
Sample problem:
A chemist, trying to identify the main component of a compact disc cleaning fluid, finds that 25.00
cm3 of the substance has a mass of 19.625 grams at 20 degrees C. The following are the names and
densities of the compounds that might be the main component:
Compound
Density in g/ cm3 at 20° C
Chloroform
1.492
Diethyl ether
0.714
Ethanol
0.789
Isopropyl alcohol
0.785
Toulene
0.867
Which of these compounds is the most likely to be the main component of the CD cleaner?
Practice Density problems:
1.
Calculate the density for the following object. If you know that the object has a mass of 7 grams
and the volume is 10 ml.
2.
Calculate the volume for the following object if you know that the object has a mass of 4 grams
and the density is 12 g/ml.
3.
Calculate the mass for the following object. If you know that the object has a density of 5 g/ml
and the volume is 5 ml.
4.
Calculate the density of a liquid in a beaker. The beaker has a mass of 15 grams when empty. The
beaker plus an unknown liquid has a mass of 22 grams. What is the density of the liquid if its
volume is 10 mL?
5.
Calculate the density of a piece of metal. The rectangular piece of solid metal has the dimensions
of 2 cm3, 3 cm3, and 2 cm3. The unidentified metal has a mass of 7 grams.
6. In the boxes (all the same size) below the dark circles represent particles of matter (all the same mass).
Which box below has the greatest density?
Why?
Classification of matter:
What is matter?
Matter- anything occupying _______ and having ______.
-
matter is complex and has many levels of organization.
4 (actually 5) phases of matter
1.
solid- rigid; fixed ____ and volume
2.
liquid- definite volume; no specific shape; takes shape of container
3.
gas-no fixed volume or shape; takes shape of container; highly compressible
4.
plasma- high energy _____; the most abundant state of matter in the universe
ex: the sun is made of plasma, blood
5.
Bose-Einstein Condensates- are gaseous superfluids (fluids with no friction) cooled to
temperatures very near ______ ____(temp. where all atoms stop vibrating)
Visual Examples:
http://www.harcourtschool.com/activity/states_of_matter/
**It takes MUCH more energy to get water into a gas phase.
Why?
What is a calorie?
Calorie- the quantity of _____ required to raise the temperature of 1 ____ of water by 1°C
Mixtures- a substance with a variable composition (made of different materials)
Examples: wood, gasoline, wine, soil, air, brass, ketchup, sugar water.
2 types of mixtures:
1. homogenous- mixtures that have evenly mixed parts (visually indistinguishable).
- homogenous mixtures are called solutions.
Examples- sugar/water, salt/water
2. Heterogeneous – mixtures that have unevenly mixed parts (visually distinguishable)
- examples: pop with ice cubes, ice cream sundae, cake, anything that is not evenly mixed.
Pure substance- substance with constant composition.
Examples: pure water, elements
** Pure substances and mixtures are opposite each other**
Question #1: All matter can be separated into two categories by asking the question "Is only one
chemical substance present in the sample being considered?"
YES - Pure Substance
NO – Mixture
Physical Changes- change in the form of a substance, not in its chemical composition.
-example: boiling, freezing
** Physical changes can be used to separate a mixture into pure compounds. **
example: boiling salt water leaves salt and evaporates the water.
3 types of physical separation methods:
1. distillation- a method that separates a mixture based on its volatility (ease at which a substance can be
turned into a vapor)
Distillation Apparatus (shown below)
2. filtration- method of separation that separates a solid and a liquid.
Filtration apparatus (shown below)
3.
Chromatography- the separation of materials based on how well they migrate (move) through a
porous material
Paper Chromatography- uses a strip of porous paper (filter paper) to separate materials. The filter
paper acts like a wick.
- this procedure is used to separate ink in police work when comparing handwritten and typewritten
print.
Example of different inks. Each manufacturer makes ink with different masses.
Black ink contains ALL colors of the spectrum and is easy to test
Compounds vs: Elements
Compound- a substance with a constant composition that can be broken down into
elements by chemical processes. A compound is 2 or more elements chemically
combined.
Example: Carbohydrate (C6H12O6), Aspirin (C9H8O4)
Chemical change- change in which a given substance becomes a new substance with different properties
and a different composition.
Example: Burning of firewood, baking a cake in the oven, fireworks.
3 tips for determining chemical changes vs: physical changes:
a. Color change
b. Smell changes
c. Sound
Elements-are substances that cannot be decomposed into simpler substances by chemical or physical means.
- elements are groups of atoms that are defined by their atomic number.
Example: Neon, Oxygen, Hydrogen, Argon, Zinc.
*there are roughly 117 known elements as of 2007
Question #2: All pure substances can be separated into two categories by asking the question "Can the
sample be further decomposed by chemical means?"
YES - Compound
NO – Element
Atomic number- the number of ______ in the nucleus of a specific atom.
Question: What is the atomic number of Cesium? Oxygen? Neon?
Atoms- Comes from the Greek word átomos meaning "the smallest indivisible particle of matter (can’t be
divided further)
- is the smallest particle still characterizing a chemical ______.
Atom composition:
- atoms are made up of 2 distinct parts:
1.
Dense Nucleus
- Contains Protons and Neutrons
** Fact: If an atoms nucleus were the size of a pea, it would weigh 250 million tons. **
Protons-Located inside the nucleus of an atom
-Has the charge of 1 fundamental unit (+1)
-Give an element its atomic ______
-Have a weight of 1.6726 × 10−27 kg
-Discovered in 1919 by Ernest Rutherford
-Proton has the weight of 1 amu (atomic mass unit)
Neutrons-Located inside the nucleus of an atom
-Has no electrical charge (neutral charge)
-Contributes to an elements atomic mass
- The number of ________ determine the isotope of the element
-Have a weight of 1.6749 × 10−27 kg
-Discovered by James Chadwick
Atomic mass- the mass of an atom at rest
- expressed in amu’s
- equal to the mass of protons, neutrons and electrons
(when the atom is motionless)
- The periodic table is arranged by proton number
and atomic mass.
**The heaviest elements (highest atomic mass) are
farthest down and to the _____ on the periodic table
- Lithium atom (notice how many protons (blue) and
neutrons (red) it has)
located
Isotopes- are atoms with the same number of ______ but different numbers of ________.
Example: Uranium in Nuclear Bombs
2.
Electron Cloud
- Contains Electrons
Electrons- Sub-atomic particles that have a _______ charge (-1)
- electrons are responsible for chemical _______ between elements.
- have a mass of 9.109 382 15(45) × 10–31 kg
- 1/1836 the weight of a proton
- discovered in 1897 by J.J. Thompson
- symbol ____
- determine an elements overall charge
Atomic Symbols on the Periodic Table:
Example Element: Sodium (Na)
23  mass number
Na  element symbol
11  atomic number
….. Another way to write the elements (as on the periodic table)
11
Sodium
Na
22.9897692
In chemistry, we call this “______ __”
Question: How would you write the element Krypton using the first method? Using the
second method?
Practice Problems

Write the symbol for the atom that has an atomic number of 9 and a mass number of 19.
How many electrons and how many neutrons does this atom have?

Write the symbol for the atom that has an atomic number of 29 and a mass number of
63.55. How many electrons and how many neutrons does this atom have?

How many protons does the element Calcium have? Neutrons? Electrons?
Fundamental Chemical Laws:
Historical Perspective: By the late 18th century Antoine Lavoisier (1743-1794) did extensive study
on combustion and found that ______ is neither created nor destroyed. This was later called the law
of conservation of mass.
*- The Law of conservation of mass set the basis for many more developments in chemistry in the 19th
century.
Frenchman Joseph Proust (1754-1826) followed in Lavoisier’s footsteps and found that a given
compound always contains exactly the same proportion of elements by mass.
- This principle came to be known as The Law of Definite Proportion.
**Proust inspired an English schoolteacher named John Dalton (1766- 1844) to think about atoms making
up elements.
In 1808, Dalton published a book called A New System of
Chemical Philosophy. In the book he outlines his Atomic Theory
Dalton’s Atomic Theory
1.
2.
3.
4.
Each element is made up of tiny particles called _____.
The atoms of a given element are identical; the atoms of
different elements are different in some fundamental
way or ways.
Chemical compounds are formed when atoms combine
with each other. A given compound always has the
same relative numbers and types of atoms.
Chemical reactions involve re-organization of the atoms--changes in the way they are bound together. _____ are
not changed in chemical reactions.
Dalton’s Original Work:
After reading Dalton’s work, Amadeo Avogadro (1776- 1856)