Download Test #1 Study Guide

Chemistry Test 1 Study Guide
Wesley Painter
Temperature Conversions
 Fahrenheit to Celsius – C = (F-32)/1.8
 Celsius to Kelvin - K = C + 273.15
Scientific Method
 Hypothesis – A tentative interpretation or explanation of the
observations. A good hypothesis is falsifiable – confirmed/rejected
by further observation.
 Scientific Law – A brief statement that summarizes past
observations and predicts future ones. Developed by a series of
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similar observations. Describes how nature behaves, nature does
not follow laws.
Scientific Theory – A model for nature that explains not only what it
does, but why. Formed by one or more well established
hypotheses.
Experiments – Highly controlled procedures designed to generate
observations.
An example of Scientific Method
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The scientist Lavoisier once observed combustion and through
these observations hypothesized, meaning he created a tentative
explanation of the observations that was falsifiable, that for
combustion to occur, oxygen was required. Through further
experimentation, or the use of highly controlled procedures to
generate observations, he came up with the law of conservation of
mass. A law is a brief statement that summarizes past
observations and predicts future ones. Through other experiments
and the use of this law, Dalton was able to come up with atomic
theory. A theory is a model for nature that explains what it does
and why.
Classification of matter
 Matter is simple to classify, and below is an easy chart to explain
how.
Matter
Variable composition?
Yes
Mixture
Uniform Throughout?
Yes
Homozygous
No
Pure Substance
Separable into simpler substances?
No
Yes
Heterozygous | Compound
No
Element
Metric Prefixes
 Prefixes added to a metric unit that multiply that unit by a powers
of 10.
Prefix
Symbol
Multiplier
Mega
M
10^6
Kilo
k
10^3
Deci
d
10^-1
Centi
c
10^-2
Milli
m
10^-3
Micro

10^-6
Nano
n
10^-9
Density
 Derived Unit – Any unit formed by combining other units (ex m/s)
 Density – Ratio of a substance’s mass to volume
o D = M/V
o Can be multiplied out so as to find any one of the variables
(i.e. D = M/V, VD = M, V = M/D)
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Be sure to remember in volume that 1 mL = 1 cm^3
Significant Figures
 There are four easy rules to significant figures:
i. Any non-zero number is significant
o Ex: 1.02
ii. A zero surrounded by two significant figures is significant.
o Ex: 1.02
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iii. If a number is followed by a decimal, it is significant.
o Ex: 120 has two sig. figs while 120. has three sig. figs.
iv. A zero after the decimal is only significant if it has numbers
before it.
o Ex: 120.0 has four sig. figs. While 0.0120 has three sig. figs.
When adding or subtracting significant figures, use the fewest
number of decimal places for the significant figures.
o Ex: 1.0362 + 0.19 = 1.23
When multiplying or dividing significant figures, use the amount
with the fewest digits for significant figures.
o Ex: 15.036/4.2 = 3.6
When using conversion factors and other things of that nature, do
not factor those numbers into how many significant figures your
answer has.
Dimensional Analysis
 Dimensional Analysis – This is basically the simple task of
converting units through the use of conversion factors, or amounts
you can multiply the original number by to get the new units.
o Ex: Convert 67.3 lbs to grams. (1 lb = 453.6 g)
67.3 lbs| 453.6 g| = 3.05 x 10^4 g
| 1 lb
|
o Note that by dividing by one pound, you cancel out the lbs
units of the original value, leaving grams as the sole value.
Scientists
 John Dalton – Proposed several things
o Atomic Theory, which has several parts:
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Each element is composed of tiny, indestructible
particles called atoms.
All atoms of a given sample of an element is the same
as an atom from a different sample of the same
element, but differs from an atom of a different
element.
Atoms combine in simple whole number ratios to form
molecules of compounds.
In a chemical reaction, atoms of one element cannot
change into atoms of another element.
o Law of Multiple Proportions:
 When two elements (called A and B) form two different
compounds, the masses of element B that combine with
1 g of element A can be expressed as a ratio of small
whole numbers.
Antoine Lavoisier – Law of Conservation of Mass, which states:
o In a chemical reaction, matter is neither created nor
destroyed.
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Joseph Proupst – Law of Definite Proportions, which states:
o All samples of a given compound, regardless of their source
or how they were prepared, have the same proportions of
their constituent elements.
J.J. Thomson – Through the use of the Cathode Ray, discovered the
electron.
o Electrons are low mass, negatively charged particles present
within all atoms.
Robert Millikan – Through the Oil Drop experiment, deduced that
the mass of an electron was about 200 times lighter than a
hydrogen atom.
Ernest Rutherford – Through his gold foil experiment in which he
shot  particles through a piece of gold foil and recorded where
these particles ended up, he disproved the plum-pudding model of
the atom and proposed nuclear theory, which has three parts:
o Most of the atom’s mass and all of its positive charge are
contained in one small core called the nucleus.
o Most of the volume of the atom is empty space, throughout
which tiny, negatively charged electrons are dispersed.
o There are as many negatively charged electrons outside the
nucleus as there are positively charged particles (protons)
within the nucleus, so that the atom is neutrally charged.
Symbols according to protons, neutrons, and electrons
 The total mass of an element is represented by the letter A.
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The atomic number of an element, which represents the number of
protons contained in the nucleus, is represented by the letter Z.
To find the number of neutrons, subtract the A value from the Z
value.
The charge of an atom is determined by whether it is an ion or not.
If it is not an ion, then the charge is 0. If it is an ion, than the
charge is indicated in the top right corner of the symbol for the
atom.
To determine the number of electrons, subract the charge of the ion
from the Z value.
Natural Abundances
 The atomic mass of an element is weighted according to the natural
abundance of each isotope. In order to calculate the atomic mass
of an element, multiply the fraction of natural occurrence by the
matching amu value for each isotope. Then add all of the
calculated numbers together to get your atomic mass.
Grams, Moles, and Avagadro’s number (Oh my!)
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Moles are the amount of a substance that you have. Because
grams mean different things across different elements, it is a way
to standardize the amount of a substance. One mole of an element
is equal to its atomic number
Avagadro’s number indicates the amount of particles, molecules,
etc. in a mole. There are always 6.022 x 10^23 particles in one
mole of a substance.
If you are given grams of a substance, you can find the amount of
moles by multiplying the grams of substance by 1 mol/ atomic
mass of the substance. This will give you the amount of moles. If
you want to see how many particles are in that certain amount of
substance, multiply the number of moles by 6.022 x 10^23/ 1 mol.
Naming Ionic and molecular compounds
 Ionic compounds are those that are made of a metal cation and a
nonmetal anion.
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When naming these compounds there are a few things to keep in
mind.
o The metal cation always goes first in the name and is showed
as is. The nonmetal anion goes second and is given as the
root + ide.
o If the metal anion is a transition metal, be sure to place the
charge of the metal in roman numeral form inside brackets
between the metal and the nonmetal.
Molecular compounds are made up of two nonmetals and are easily
distinguished from ionic compounds because of this.
Naming of molecular ions requires you to know the prefixes that
indicate the number of a certain thing.
o For the first element, indicate the number that exist in the
molecule with a prefix.
o Do the same for the second molecule, but be sure to use the
root and add ide to the end of the molecule root.
Naming Acids
 Acids are compounds that release H+ ion when dissolved in water.
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Binary acids are composed of only two elements, Hydrogen and a
nonmetal.
o To name these acids, simply add hydro to the front of the
root of the nonmetal, ic to the end of the root name of the
nonmetal, and follow that with acid. This only works if the
acids are aqueous and not if they are in a gaseous state. If
they are in the gaseous state, name them as a molecular
compound
Oxyacids are acids that contain a hydrogen and an oxyanion (an
anion containing a nonmetal and oxygen). These are the
polyatomics ions that are listed below.
o To name these acids, simply determine whether the oxyanion
ends with ate or ite. If it ends with ate, change the ate to an
ic and add acid after. It it ends with ite, replace the ite with
ous and add acid onto the end.
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Polyatiomic ions and their names are as follows:
Formula
Acetate
Carbonate
Hydrogen Carbonate
Hydroxide
Nitrite
Nitrate
Chromate
Dichromate
Phosphate
Name
C2H3O2CO3-2
HCO3OHNO2NO3CrO4-2
Cr2O7-2
PO4-3
Hydrogen Phosphate
Dihydrogen Phosphate
Ammonium
Ammonia
Hypochlorite
Chlorite
Chlorate
Perchlorate
Permanganate
HPO4-2
H2PO4NH4+
NH3+
ClOClO2ClO3ClO4MnO4-
Sulfite
Hydrogen Sulfite
Sulfate
Hydrogen Sulfate
Cyanide
Peroxide
SO3-2
HSO3SO4-2
HSO4CNO2-2
(note that I and BR
form the same
pattern as Cl)