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Scientific Notation
If there is no decimal place a decimal at the end of the number
Move the decimal so that the new number is between 1-10
Write the new number and place a (x10) after the number
Place an exponent above the 10, the exponent should be the number of places the decimal was moved.
If the original number was greater than 1, than the exponent will be positive. If the number is less than
one, the exponent will be negative
Example: 45,000 = 4.5 x 104
0.00045 = 4.5 x 104
** Use EE button on calculator for x10
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Rules for Significant Figures
No decimal: Count Right to Left- 24,500 count  has 3 significant figures
Decimal: Count Left to Right- 0.045 count  has 2 significant figures
All non-zero digits (1-9) are significant
ZEROS WHICH ARE PLACE HOLDERS ARE NOT SIGNIFICANT
All non-zero digits (1-9) are significant.
Zeros between non-zero digits are significant. Ex: 3004 has 4 significant figs.
Zeros to the left of the first non-zero digit are not significant. Ex: 0.004 has 1 significant fig.
If a number ends in zeros to the right of the decimal point, those zeros are significant.
number 40.0 has 3 significant figures
Ex: The
Multiplication and division, the result may have no more significant figures than the factor with the fewest
number of significant figures.
Example:
2.52
x
(3 sig figs)
(smallest)
1.003
(4 sig figs)
= 2.52756  recorded to 2.53
=
(3 sig. figs)
Adding and subtracting: Add or subtract the numbers. The final answer can contain only as many decimal
places as found in the measurement with the fewest number of decimal places.
Example: 134.052 m
+
1.23 m =
135.282  rounds to 135.28
(3 decimal places) (2 decimal places)
(2 decimal places)
________________________smallest_________________________________________
Density (mass unit/volume unit) = Mass (unit) ÷ Volume (unit)
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Specific heat (c) (units) = calories / (grams x C) or joules / (grams x C)
Heat released (cal or J) = mass (g) x Specific heat (choose one unit above) x temp change (ºC)
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Conversions: When converting units make sure the unit you are looking for is on top of the conversion fraction
and the unit given is on the bottom of the conversion fraction so the units given can cancel.
1 dozen
Example:
132 pencils = ________ dozen
132 pencils x ---------------- = 11 dozen
12 pencils
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Lewis / Electron-dot diagrams
1. Write symbol of element
2. Place the correct number of dots around the symbol (The number of dots equals the number of valance
electrons or the group / roman number the element is in)
3. Spread out the dots before doubling up
●
Aluminum = Group III  ● Al ●
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Nitrogen = Group V  ● N ●
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Metric Conversions
Units
Length
meters
(Decreasing
order)
Kilo:
0.001 Km
1m
Base unit:
Centi:
100 cm
1000 mm
Milli:
1,000,000 µm
Micro:
1,000,000,000 nm
Nano:
Mass
grams
0.001 Kg
1g
100 cg
1000 mg
1,000,000 µg
1,000,000,000 ng
Volume
liters
0.001 KL
1L
100 cL
1000 mL
1,000,000 µL
1,000,000,000
nL
1cm3 = 1 mL
When choosing the ratios from the table above, one part of the ratio goes on top of the fraction and the other goes on the
bottom. The ratio should be set up so that the top of the ratio should have the units that you are looking for and the
bottom should be the units that you start with.
Example:
2 mm = _______ cm
Get from chart above
100 cm
2 mm  ---------------- = 0.2 cm
1000 mm
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Elements
Nucleus is positively charged
Number of neutrons= atomic mass - atomic number
Atomic number= number of protons
Number of protons= number of electrons
Valence electrons= group number
Electron: negative sub particle (outside of the nucleus) CHARGE= -1
Proton: positive sub particle (found in nucleus) CHARGE= +1
Neutron: neutral sub particle (found in nucleus) CHARGE= 0
Periodic table of elements: list of elements in order
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Percent Error Formula
Percent error = [Measured value – Accepted value]  Accepted value x 100
Percent Composition
Percents
1. Place each part of the mixture over the total
2. Each fraction is divided
3. Each decimal is multiplied by 100
Percent composition
Formula= Percent composition = (Mass of element x subscript)  (mass of compound) x 100
 the mass of each element is multiplied by their subscript
 the molar mass of the compound is the sum of the elements
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Writing Formulas
Ionic Compounds: oppositely charged ions. A metal and nonmetal(s)
Binary Ionic Compounds
Criss-cross to arrive at subscripts
Ex:
Sodium nitride = Na+1 and N -3  Na3N
Ternary Ionic Compounds
Aluminum hydroxide = Al+3 and (OH-1)  switch numbers to get Al(OH)3
Binary Molecular (Covalent) Compounds:
Prefixes (see chart below) become subscripts: Ex: Trinitrogen pentabromide  N3Br5
Naming Compounds
Binary Ionic:
1. One metal and nonmetal
2. If metal is from transitional group must use roman number if not just name metal
3. Nonmetal drops ending and adds “ide”
Example: CaCl2
Example: Cr2S3
Calcium chloride
Chromium (IIII) sulfide (Roman number is found as other subscript)
Ternary Ionic Compounds
1. One metal and more than one nonmetal
2. If metal is from transitional group must use roman number if not just name
3. Nonmetal group gets name from polyatomic ion chart.
Example: Ca(NO3)2 Calcium nitrate
Example: Fe(OH)2
Iron (II) hydroxide (Roman number is found as other subscript)
Binary Molecular (Covalent) Compounds: Both negative charged ions. Both non-metals
(Use prefixes as subscripts)
1. Second nonmetal drops ending and adds “ide” Ex: N2O3 Dinitrogen trioxide
Prefix
Mon
Di
Tri
Tetra
Penta
Number of atoms
1
2
3
4
5
Prefix
Hexa
Hepta
Octa
Nona
Deca
Number of atoms
6
7
8
9
10
Drawing Bohr diagrams
1. The number of protons and neutrons are place in the nucleus.
2. The electrons are placed in energy levels according to the maximum occupancy.
(Fill each shell in numerical order until all electrons are used)
Energy Level Maximum number
of electrons
1
2
2
8
3
18
4
32
Ex:
Argon #18
18p+
22 n0
﴿
2e﴿
﴿
8e﴿
﴿
8e﴿
Temperature Conversions using formulas
1. To change Celsius to Fahrenheit: Take the given temperature and multiply by 1.80 then
press equal then add 32 then press equal.
2. To change Fahrenheit to Celsius: Take the given subtract 32 then press equal then multiply
the number by 0.56 then press equal.
3. To change Celsius to Kelvin: Add 273 to the given temperature
4. To change Kelvin to Celsius: Subtract 273 from the given temperature.
Types of Equations
Combination:
A + B  AB
Decomposition:
AB  A + B
Single Replacement:
A + BC  AC + B
A + BC  BA + C
Double Replacement:
Complete Combustion:
(A is metal)
(A is a nonmetal)
AB + CD  AD + CB
AB + O2  CO2 + H2O
Incomplete Combustion:
AB + O2  CO + H2O
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Scientists
JJ Thompson discovered the negative part of the atom
Rutherford discovered the center of the atom
Aristotle believed all matter was made of earth, fire, wind and water
Mendeleev organized the elements
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Atomic Mass
Diatomic Elements: H2, N2, O2,, F2, Cl2, Br2, I2
Double the mass
Example: Bromine: 79.9 x 2= 158.80
Compounds
Multiply the subscript of each element by the element’s atomic mass, and then add.
Example: H2 O
H2= 1.01 x 2 = 2.02
O= 15.99 x 1 = 15.99
Atomic Mass : 18.01
Compounds with Parenthesis
Distribute number outside of parenthesis to numbers inside parenthesis, multiply the subscript of each element
by the element’s atomic mass, and then add.
Example: Ca(OH) 2
Ca O2 H2
Ca: 1 x 40.07 = 40.07
O2: 2 x 15.99 = 32.00
H2: 2 x 1.01 = 2.02
74.09
The Mole
Mass to Moles
Take the number of grams given and divide by the mass of the compound from the periodic table
Example: 40.0 grams of H2O=
40g H2O / ( 2xH (1.01) + 1xO (16.0))
40g H2O / (2.02 + 16)
40g H2O/ 18.02= 2.22 moles
Moles to Mass
Take the number of moles given and multiply by the mass of the compound from the periodic table
Example: 4.00 moles of H2O =
4.0 mol H2O x (2 x H (1.01) + 1 x O (16.0))
4.0 x (2.02 + 16) = 72.08 grams
Moles to Particles
Take the number given and multiply by 6.02 x 1023
Example: 4.5 moles of H2O=
4.5 mol H2O x 6.02 x 1023
2.71 x 1024 particles
Particles to Moles
Take the given number and divide by 6.02 x 1023
Example: 4.50 x 1024 particles of H2O=
4.50 x 1024 / 6.02 x 1023= 7.47 moles