Introduction to Chemistry
Matter
Matter
Anything that has mass and volume
Mixtures
Pure Substances
Has its own uniques set of chemical
and physical properties
Heterogeneous Mixtures
Homogenous Mixtures
Compounds
Elements
A mixture that has visibly different parts
(Ex: Granite, chocolate chip cookie, can
be separated by physical properties.)
Also known as solutions.
Does not have visibly different parts, but
can be separated by physical props.
(Ex: salt water, air)
Composed of two or more elements
Ex: Water, rust, carbon dioxide.
Can be broken down into elements
by their chemical properties.
A substance that cannot be broken
into smaller pieces and
maintain the properties of that
element. (ex: Oxygen, iron)
Atoms
Composed of Protons,
Neutrons and Electrons
Measurements in science are handled using the metric system:
length - meters
volume - liters
mass - grams
You can use very large or very small numbers like
5 000 000 g
or
0.000 000 005 g
You can rewrite them in scientific notation
5 x 10 6 g
or
5 x 10 -9 g
Or you can use metric prefixes that represent exponential values of
10
5 Mg (M=106)
or
5 ng (n = 10 -9)
Prefix
Symbol
Meaning
Exponential
Notation
Exa
E
1,000,000,000,000,000,000
1018
Peta
P
1,000,000,000,000,000
1015
Tera
T
1,000,000,000,000
1012
Giga
G
1,000,000,000
109
Mega
M
1,000,000
106
Kilo
k
1,000
103
Hecto
h
100
102
Deka
da
10
101
-----
----
1
100
Deci
d
0.1
10-1
Centi
c
0.01
10-2
Milli
m
0.001
10-3
Micro

0.000001
10-6
Nano
n
0.000000001
10-9
Pico
p
0.000000000001
10-12
Femto
f
0.000000000000001
10-15
Atto
a
0.000000000000000001
10-18
Scientific Notation
Try on your own:
140 000 000 000
1.4 x 10 11
34 000
3.4 x 10 4
564 878 000
5.64878 x 10 8
0.000 000 000 000 26
2.6 x 10 -13
0.000 000 511
5.11 x 10 -7
Scientific Notation
A way to simplify very large or very small numbers
9 000 000 000
= 9.0 x 10 9
= 3.4 x 10 -7
0.000 000 34
Rules
1.
You may only have one digit to the left of the decimal
2.
That digit must be > 1 but < 9
3.
Count the number of places you have moved the decimal from its
original location and make it the exponent in
x 10
?
If the decimal is moved left the exponent is +
If the decimal is moved right the exponent is -
How much do you remember about
significant digits??
Identify the number of sig figs in each of the
following numbers.
:
a.) 0.0023 g
b.) 2.40 L
c.) 2 centuries
d.) 250 inches
e.) 432 ft
f.) $28.04
Answers: a)2, b.) 3, c) infinite, d) 2, e)3, f) 4
Significant figures are a way to deal with uncertainty in
Measurement.
Rules for significant figures:
1. All nonzero digits are significant
2. All zeros between non zero digits are significant
3. Leading zeroes are NOT significant
4. Trailing zeroes are NOT significant if there is no decimal point in the
number.
5. Exact numbers such as counted numbers or numbers in a
Definition like 1 dozen =12 pieces do not have an affect on a
Calculation, they are considered to have an infinite number of
Significant figures.
Try again:
a) 347 mL
b) 0.0045 g
c) 100 oz
d) 85.0 mL
e) 4075 kg
f) 0.0560 m
g) 520. g
h) 8.000 g
i)
0.302 lb
j) 1006 m
Significant Figures in calculations
Muliplication and Division
Find out how many sig figs are in each number in the problem.
2.36 x 1.631
3
Do the math
4
2.36 x 1.631 = 3.84916
Your answer must now be rounded off to the lowest
number of sig figs present in the problem, in this case, 3
Answer 3.85
You can only be as certain as your least certain instrument.
Practice (Rules for multiplication and Division are the same.)
1.) 12.3 x 3.6 x 0.4356 =
19.288368 =
19
2.) 15 ÷ 4.21 =
3.56294537 =
3.6
3.) 3.145 x 103 x 6.1 x 1012 = 1.91845 x 1016 =
4.) 3.18 x 103 x 6.4 x 10-4 =
2.0352
=
1.9 x 10 16
2.0
Addition and Subtraction
1. Line up numbers at decimal point, complete addition of subtraction
2. Where number is rounded depends on the least certain value,
meaning the place value closest to the decimal.
12.364 + 121.1 = ?
12.364
121.1
133.464
Tenths place value is least certain
so round at that place value
=
133.5
Person
Reading
1
20.15 mL
2
20.14 mL
3
20.16 mL
This buret is graduated
by 0.1 mL increments.
Your measurement can
be certain to the tenths
place value. Even
though you can predict a
number in the
hundredths place value,
it may be different
depending on who you
are. Therefore, it is an
uncertain number.
Since each person has a
variance of 0.01 mL, we say
the measurement is
20.1X + 0.01 mL
This instrument is called an
analytical balance. It reads to 4
places past the decimal point.
With uncertainty factored in,
we would read this
measurement as
89.2863 + 0.0001 g
On an instrument this
sensitive the last number
fluctuates constantly so even
though it has a digital readout
you may have it reading 2
numbers without settling on
either one.
Precision and Accuracy
Completely random
data.
Somewhat organized.
Very organized. All
All information
information collected
collected in one
in expected location
location
Precision - Reproducibility for each trial of an experiment
Accuracy - Agreement with a known value
Temperature scales in science
Metric System - Celsius after the Swede Andres Celsius.
He set freezing of H2O as 0°C and boiling at 100 °C then
broke up the scale into 100 pieces.
Kelvin - Based on research in gas laws done by Lord
Kelvin. He found that all gases eventually reach the same
temperature if cooled, -273 °C . He set this as O K or
Absolute Zero.
To convert between Celsius and Kelvin:
K = C + 273
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Some important people to know!
(Because they discovered the particles in
an atom or something about them.)
Democritus
First credited with the “idea’ of the
atom. Theorized that there were
indivisible particles that
made up all matter. Idea was negated by Socrates/Aristotle (who was
more popular) and was not accepted again until late 1700’s when John
Dalton determined that matter is made up of smaller particles.
Dalton
Law of Conservation of Mass
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Thomson
J.J. Thomson - Credited with the
discovery of electrons. Thompson
wanted to discover the makeup of
the atom and so did experiments
that led him to the discovery that
there were negatively charged
particles in the atom.
Since atom are neutral particles he
also guessed that there was some
positively charged component to the
atom.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Robert Millikan - Determined the charge of an
electron.
Rutherford
Ernest Rutherford - Discovered a large mass that was
reflecting back electrons in an atom. Named it
“nucleus”. Determined that the positive portion of an
atom was located in the center.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
The pieces of an atom
Charge
Location
Size in relation to
Each other
Protons
Positive
Nucleus
1 amu
Neutral
Nucleus
1 amu
Negative
Electron Cloud
1/1879 amu
Neutrons
Electrons
Atomic
Number
Reading the periodic table
6
C
Carbon
12.011
Symbol
Name
Atomic Mass
Atomic Symbol - An abbreviation of an element’s name. May or may
not match the beginning of our language.
Carbon -
C
Sodium-
Na from latin Natrium
Lead-
Pb from latin Plumbum
Atomic Number - Tells number of protons and electrons in an atom.
Atomic Mass - Sum of protons and neutrons in atom
A shortcut way of writing out this information is
12C
6
This gives
isotopic mass
atomic number
Chemical
Symbol
Symbol
Name
Atomic
#
Atomic
Mass
Protons
Selenium
25
183.85
Ca
Sodium
39
Neutrons
Electrons
Symbol
Element Atomic
#
Isotope
Mass
Protons
Neutron
s
Electro
ns
SO3 -2
CrO4 -2
Na+1
NH4+1
Fe +2
O2
-2
Hg2
+2
ClO-1
dichromate
aluminum
lead (IV)
potassium
bromide
selenide
cyanide
Density
D = m/V
Know your volume formulas for 3D shapes
V=bh
V=lwh
V=4/3p r3
V=1/3p r2h
The density of osmium is 22.57 g/cm3. If a 1.00
kg rectangular block of osmium has two
dimensions of 4.00 cm x 4.00 cm, calculate the
third dimension of the block.
An iron cylinder has a density of 7.874 g/cm3. If the cylinder
weighs 53.25 g and has a height of 6.0 cm, Find the diameter of
the cylinder.
Elements were thought to be
limited in number
Early version of the periodic table.