Transcript Chemistry

Important things to remember in chemistry
MEMORIZE the starred pages
Introduction and Measurement
Chemistry is
• the study of matter and the changes it undergoes
(transformations)
• the study of reactions and interactions among
different types of matter
• the study of connections between macroscopic and
submicroscopic events
• the science that seeks to understand the behavior of
matter by studying the behavior of atoms and molecules
Memorize for week 1
3
Memorize for week 1
International System of Units (SI)
4
Memorize for week 2
5
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A Comparison of Temperature Scales
K = 0C + 273.15
273 K = 0 0C
373 K = 100 0C
0C
= 5 x (0F – 32)
9
0F
= 9 x 0C + 32
5
32 0F = 0 0C
212 0F = 100 0C
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Significant Figures
• Any digit that is not zero is significant
1.234 kg
4 significant figures
• Zeros between nonzero digits are significant
606 m
3 significant figures
• Zeros to the left of the first nonzero digit are not significant
0.08 L
1 significant figure
• If a number is greater than 1, then all zeros to the right of the
decimal point are significant
2.0 mg
2 significant figures
• If a number is less than 1, then only the zeros that are at the
end and in the middle of the number are significant
0.00420 g 3 significant figures
http://www.roch.edu/people/tebrown/pages/sigfig2.htm
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Significant Figures
Exact Numbers
Numbers from definitions or numbers of objects are considered
to have an infinite number of significant figures
The average of three measured lengths; 6.64, 6.68 and 6.70?
6.64 + 6.68 + 6.70
= 6.67333 = 6.67 = 7
3
Because 3 is an exact number
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CALCULATIONS with Significant Figures
Addition or Subtraction
The answer cannot have more digits to the right of the decimal
point than any of the original numbers.
89.332
+1.1
90.432
3.70
-2.9133
0.7867
one significant figure after decimal point
round off to 90.4
two significant figures after decimal point
round off to 0.79
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CALCULATIONS with Significant Figures
Multiplication or Division
The number of significant figures in the result is set by the original
number that has the smallest number of significant figures
4.51 x 3.6666 = 16.536366 = 16.5
3 sig figs
round to
3 sig figs
6.8 ÷ 112.04 = 0.0606926 = 0.061
2 sig figs
round to
2 sig figs
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Dimensional Analysis Method of Solving Problems
1. Determine which unit conversion factor(s) are needed
2. Carry units through calculation
3. If all units cancel except for the desired unit(s), then the
problem was solved correctly.
given quantity x conversion factor = desired quantity
given unit x
desired unit
given unit
= desired unit
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A law is a concise statement of a relationship
between phenomena that is always observed and
measured to be the same under the same
conditions. Ex. Law of Acceleration
Force = mass x acceleration
A natural law compactly summarizes patterns in a large amount of data that often
apply only under special conditions and are descriptions of nature, not facts or
explanations
Ex. Law of Gravity – “What goes up, must come down”
m1 m2
ForceGravity = G _________
2
d
A scientific law is a statement that summarizes all past observations and predicts
future observations
Ex. Law of Conservation of Mass – “In a chemical reaction, matter
is neither created nor destroyed.”
CH4 + 2 O2
--> CO2 + 2 H2O
A law allows you to predict future observations
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Atoms, Molecules and Ions
Elements and compounds:
names and formula writing
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Our definitions
• Atom: smallest, independent, uncharged, unique unit of matter
ex. An atom of hydrogen, H
H
• Molecule: two or more atoms bonded together chemically;
electrically neutral ex. A molecule of hydrogen gas H2
H-H
• Ion: an atom that has acquired a charge, either positive (+), called
cation or negative (-), called anion ex. Hydrogen ion
H+
• Polyatomic ion: a group of atoms bonded to each other but carrying
an over-all charge, either positive (+) or negative (-)
ex. Hydroxide anion, OH-
O-H -
These terms are used to describe matter on the basis of the particles
they are made up of
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Orbital: The pathway of an electron
• It is the region in space where the probability of finding an
electron is greatest
• Every set of orbitals is also known as an energy level;
• It is related to the period (horizontal row) in the periodic
table and represents the relative distance from the
nucleus
• An orbital can contain a maximum of 2 electrons per
individual orbital
• Electrons have a specific amount of energy and can give
off or absorb energy as they enter or leave an orbital
• The basic shape is a sphere but becomes more complex as
more space is available father from the nucleus
• An orbital is not physical material but is defined by the
presence of an electron
http://winter.group.shef.ac.uk/orbitron/AOs/1s/index.html
Types of compounds and how they
are named
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Memorize for week 3
Memorize these names of common negative ions and their charges
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Memorize these Common Polyatomic Ions
and their charges
Memorize for week 3
Name
Formula
Name
Formula
acetate
carbonate
hydrogen carbonate
(aka bicarbonate)
hydroxide
nitrate
nitrite
chromate
dichromate
ammonium
C2H3O2–
CO32–
hypochlorite
chlorite
ClO–
ClO2–
OH–
NO3–
chlorate
perchlorate
sulfate
sulfite
NO2–
CrO42–
ClO3–
ClO4–
SO42–
SO32–
hydrogen sulfate
(aka bisulfate)
HSO4–
Cr2O72–
NH4+
hydrogen sulfite
(aka bisulfite)
HSO3–
Tro, Chemistry: A Molecular
Approach
HCO3
–
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Periodic Pattern of Polyatomic Ions
-ate groups
3A
BO
4A
-3
3
5A
6A
-2
3
-1
NO 3
-2
SiO 3
-3
PO 4
CO
AsO
-3
4
-2
SO 4
ClO
-2
SeO 4
-1
BrO 3
TeO
Tro, Chemistry: A Molecular
Approach
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7A
-2
4
-1
3
-1
IO 3
Memorize for week 3
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Memorize for week 3
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Memorize for week 3
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Naming = Nomenclature
All Compounds
metal nonmetal
nonmetal nonmetal
has H @ start
or H that can
be donated