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Chem MT 1-6 Cheat Sheet by

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The Scientific Method

Chem­istry is the science that deals with the materials of the universe and the changes that these materials undergo.
Steps:
1. State the problem and collect data (make observ­ations)
2. Formulate hypoth­eses. A hypothesis is a possible explin­ation for the observ­ation.
3. Preform Experi­ments. Gather new inform­ation that allows us to decide whether the hypothesis is supported by the new inform­ation we have learned

Measur­ements and Calcul­ations

Scientific notation expresses a number as a product of a number between 1 and 10 and the approp­riate power of 10.
Ex. (100= 1.0×102 , 0.010=­1.0­×10­-2)
If the decimal is moved to the left, the power of 10 is positive ; if the decimal is moved to the right, the power of 10 is negat­ive.

Unit Prefixes

Signif­icant Figures

The numbers recorded in a measur­ement are called sign­ificant figures.
1. Nonzero integers always count as signif­icant figures. Ex. (4567 has four nonzero integers that count as signif­icant figures.)
2. Zeros.
a. leading zeros never count as signif­icant figures. Leading zeros are all zeros that precede nonzero integers.
b. captive zeros always count as signif­icant figures. Captive zeros are zeros that fall in between two nonzero digits.
c. trailing zeros are sometimes signif­icant figures. Trailing zeros are zeros right at the end of a number. They are only signif­icant if the number is written with a decimal. (Ex. The number 100 only has one SF 1 ; but the number 100. has three SF.
3. Exact Numbers never limit the number of signif­icant figures in a calcul­ation.
Sign­ificant figures also apply to scientific notati­on.

Temper­ature Conversion

TC Equations

Temper­ature in Kelvins = Temper­ature in Celsius + 273
Temper­ature in Celsius = Temper­ature in Kelvin - 273
Temper­ature in Fahrenheit = 1.80( Temper­ature in Celsius) +32
Temper­ature in Celsius = Temper­ature in Fahrenheit - 32 / 1.80

Density, Mass, and Volume

Elements and Compounds

An elem­ent is a substance that cannot be broken down into other substances by chemical means.
When elements combine, they form comp­oun­ds, which are substances that can be broken down into elements by chemical means.

Pure Substances and Mixtures

A pure substance is either an element or compound.
A mixture can be defines as something that has variable compos­ition.
Mixtures can be classified as either homoge­neous or hetero­gen­eous.
A homog­eneous mixture is the same throug­hout. This type of mixture is also called a solution.
A heter­oge­neous mixture contains regions that have different properties from those of other regions.
These mixtures can be separated through dist­ill­ation and filt­rat­ion.
 

Mixtures

Dalton's Atomic Theory

1. Elements are made of tiny particles called atoms.
2. All atoms of a given element are identical.
3. The atoms of a given element are different from those of any other element.
3. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms.
4. Atoms are indivi­sible in the chemical process. Atoms are not created nor destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.

Atom Structure

Isotopes

Periodic Table

Ions

An ion is an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
A cation is a positively charged ion; an ion that has lost electrons.
An anion is a negatively charged; an atom that has gained electrons.
Alkali Metals are the most reactive metals that can form cations easily by only needing to lose one valence electron.
Halo­gens are the most reactive nonmetals that can form anions easily by only needing to gain one valence electron.
Noble Gasses have 8 valence electrons so they are already stable.
An ionic bond is a chemical bond resulting from the attraction between oppositely charged ions.
A chemical compound must have a net charge of 0 (zero)

Ionic charges

 

Common Simple Cations and Anions

Cation
Name
Anion
Name
H+
hydrogen
H-
hydride
Li+
lithium
F-
fluoride
Na+
sodium
Cl-
chloride
K+
potassium
Br-
bromide
Cs+
cesium
I-
iodide
Be2+
beryllium
O2-
oxide
Mg2+
magnesium
S2-
sulfide
Ca2+
calcium
Ba2+
barium
Al3+
aluminum
Ag+
silver
Zn2+
zinc

Common Type II Cations

Ion
Systematic Name
Older Name
Fe3+
iron(III)
ferric
Fe2+
iron(II)
ferrous
Cu2+
copper(II)
cupric
Cu+
copper(I)
cuprous
Co3+
cobalt­(III)
cobaltic
Co2+
cobalt(II)
cobaltous
Sn4+
tin(IV)
stannic
Sn2+
tin(II)
stannous
Pb4+
lead(IV)
plumbic
Pb2+
lead(II)
plumbous
Hg2+
mercur­y(II)
mercuric
Hg22+
mercury(I)
mercurous
Mercury(I) ions always occur bound together in pairs to form Hg22+.

Nomenc­lature

Common Polyatomic Ions.

Rules for Naming Acids

If the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix -ic attatched to the rootname of the element.
Ex. HCl= hydro­-c­hlo­r-ic acid
2. When anions contain oxygen, the acid name is formed from the root name of the central element of the anion or the anion name with the suffix of -ic or -ous.
When the anion name ends in -ite, the suffix -ic is used.
(Ex. H2SO4 = SO42-­(s­ulfate) = Sulfric Acid)
When the anion name ends in -ite, the suffix -ous is used in the acid name.
(Ex. H2SO3 = SO32- (sulfite) = Sulfurous acid)

Chemical Equations

We represent a chemical reaction by writing a chemical equation in which the chemical reactions (the reac­tan­ts) are shown to the left of an arrow and the chemicals are formed by the reaction (the prod­ucts) are shown to the right of the arrow.
In the process of balancing equations is that atoms are conserved in a chemical reaction.
The identities (formulas) of the compounds must never be changed in balancing a chemical equation.

Balancing Equations

Step 1 Read the descri­­ption of the chemical reaction.
Step 2 Write the unbalanced equation that summarizes the inform­ation from step 1.
Step 3 Balancing the equation by inspec­tion, starting with the most compli­cated molecule. Proceed element by element to determine what coeffi­cients are necessary so that the same number of each type of atom appears on both the reactant and the product side.
Step 4 Check to that the coeffi­cients used, give the same number of each type of atom on both sides of the arrow. Also check to see that the coeffi­cients used are the smallest integers that give the balanced equations. This can be cone by determ­ining whether all coeffi­cients can be divided by the same integer to give a set of smaller integer coeffi­cients.

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