SOL Notes #1 Independent variable – that which is changed by experimenter Dependent variable – part of the experiment that is measured Control – standard for comparison Constants – variables not changed Why is it important to perform many trials in an experiment? Qualitative – use physical characteristics to describe Quantitative – numerical data Physical vs. Chemical Properties Sig figs „ all digits, 0 after digit and decimal, 0 in between sig figs „ uncertain digit is the last digit -ex 2.457

Conversions – get units to cancel out 1000 mL = 1 L 1000 mg = 1 g Density = mass volume Instruments Separation Techniques … filtration … decanting … chromatography

Scientists Most Important

• Dalton – atomic theory

• Thompson – discovered electron, plum pudding model, cathode ray tube experiment • Rutherford – discovered nucleus, gold foil experiment • Bohr – planetary model of atom Could still appear on test

Accuracy & Precision … accuracy – close to the true value (“theoretical” value) … precision – close to each other Scientific notation • only one digit in front of decimal • exponent is negative if number is < 1 o Ex. 0.00567 would be 5.67 x 10-3 • exponent is positive if number is >1 o Ex. 567,000 would be 5.67 x 105

• Democritus – all things made of particles

• Millikan – discovery of charge & mass of electron, oil drop experiment • Mendeleev – periodic table by atomic mass • Moseley – periodic table by atomic number • Heisenberg – uncertainty principle (can’t know position and momentum of electron at the same time)

Chemistry SOL Notes #2 (REG) Percent error = (Experimental – True) X 100 True

1

“theoretical”

2

Atomic mass = weighted average of all isotopes ¾ multiply % of each isotope times mass of each isotope Ex) What is average atomic mass of a newly discovered element if it is 12% X-76 and 88% X-77 Cation – positive charge, lost electrons Anion – negative charge, gained electrons Indicating # of protons, electrons and neutrons 22 Al+3 K 11 Na

F-1

Electron Configuration s, p, d, f • Maximum number of electrons per orbit: 2 • Hund’s rule – electrons fill equal energy orbitals singly before pairing • octet rule – atom is most stable when it has 8 valence electrons Write the electron configuration for: Carbon ____________________________ Write the electron configuration for: Chlorine ___________________________ Write the noble gas configuration for: Calcium __________________________ Write the noble gas configuration for: Phosphorus _________________________ 2

4

2

Al 2

Which element is in the same group as 1s 2s 2p ?

Atomic number = protons Mass number = protons + neutrons Isotope = same # protons, different # neutrons Ex. Carbon-13, C-13, 136 C

Which element has electron configuration: ns np

Which element has electron configuration: ns

Al

K

Ne

S

K

Mg Be

Ne

S

Al

C

Indicate # of valence electrons for each element Sulfur magnesium aluminum

chlorine

Draw Lewis dot structure for each atom Sulfur magnesium

chlorine

aluminum

Chemistry SOL Notes #3

(Reg)

Group/family – column „ elements in same column have similar characteristics…WHY? Period – row Ionic compounds – a (+) and (-) charge; metal + nonmetal 1) cross charges 2) NO prefixes Covalent compounds – nonmetal + nonmetal 1) NO criss-cross 2) Use prefixes according to subscripts (mono-, di- tri-, ….) Indicate if each of the following is ionic or covalent and name N2O4 _______________________

K3N _______________________

Indicate if each of the following is ionic or molecular and give formula Carbon tetrachloride ___________ sodium phosphide ____________ Transition metals – roman numeral indicates charge, reverse criss-cross Iron III oxide _____________

Nickel II phosphide ___________

Cr2O3

Cu(NO3)2 _______________________________

_____________________________

Diatomic molecules: Br I N Cl H O F Polyatomic Ions NH4+1 ammonium

CO3-2

carbonate

SO4-2

OH-1

hydroxide

sulfate

NO3-1 nitrate

PO4-3 phosphate

Acids – begin with hydrogen; pH + pOH = 14 use acid rules: hydro--ic and “ate-ic ite-ous” Bases – end in –OH ex: Al(OH)3 aluminum hydroxide Indicate the number of atoms and elements for each compound:

Mg(NO3)2

Al2(SO4)3

NH4OH

Chemistry SOL Notes #4 Reg Chem

Molarity = moles Liters

M1V1 = M2V2

1) What is the molarity if 585 grams of NaCl is dissolved in 5 L of water? 2) How many grams of K3N are needed to make 2.3 L of a 0.45 M soln? 3) What is the final concentration if 80.0 mL of a 5.00 M solution are diluted to 800.0 mL? 4) How many milliliters of 2.00 M H2SO4 are needed to provide 0.250 mole of H2SO4? Percent Composition = grams element/grams compound x 100 CO2 Al2(SO4)3

% C = _______ %Al = ______

% O = ______ %S = ______ %O = ______

Empirical and Molecular Formula Problems 1) 2) 3) 4)

check molar mass if given find percent composition of one element narrow down choices find percent comp. of second element

1) A compound has 64% nitrogen and 36% oxygen. What is its empirical formula? A) NO2 B) N2O4 C) N2O D) N4O2 2) A compound is composed of 86% carbon and 14% hydrogen and the molar mass is 28 g/mol. What is the molecular formula for this compound? A) CH2 B) C2H4 C) CH16 D) C2H10 3) What is the molecular formula of a substance that has an empirical formula of C2H5 and a molecular mass of 58 g/mole? A) C2H5 B) C5H2 C) C4H10 D) C6H15

Chemistry SOL Notes #5 (Reg) Double Replacement: AB + CD  AD + CB Aluminum bromide + Calcium oxide  Single Replacement: A + BC  AC + B positive replaces positive negative replaces negative Potassium + Aluminum fluoride  Synthesis: A + B  AB Sodium + nitrogen  Decomposition: AB  A + B H2O  ** key points for reactions** 1) If element is by itself, check it for diatomic (BrINClHOF) 2) If element is with something, check for possible criss-cross 3) Roman numerals indicate the charge of a transition metal

Half life problems 1) set up Time/Amount chart with time “0” 2) Put the “half-life” in the time column under “0” 3) Put the largest amount given in the top of the amount column 4) Add the half-life for each increment in the time column 5) Divide the amount in half for each increment in the amount column 6) Continue until you reach level they ask for Ex) An element Z has a half life of 20 days. If you start with 200 grams of element Z, how much will be left after 60 days?

Ex Using the reaction above, how many moles of H2O can be made if you have 15 moles of oxygen

Ex Using the reaction above, how many liters of CO2 can be made if you have 200 Liters of O2

128 grams CO2 at STP = _________ L of CO2

Ex Using reaction above, calculate how many grams of C3H8 are needed to make 176 grams of CO2

C3H8 + 5 O2 o 3CO2 + 4H2O

1) Determine what is given and what is needed 2) Set up units to cancel 3) Insert values on chart

Steps

Stoichiometry – converting between different compounds

89.6 L of O2 at STP = ____________ grams O2

3.45 x 1024 molecules N2O4 = ____________ grams N2O4

Convert the following

Molar Conversions -- staying with the same compound 22.4 L of gas at STP = 1 moles of gas at STP (standard temperature and pressure) 6.02 X 1023 particles = 1 mole

SOL Review Notes #6

Chemistry SOL notes #7 Exothermic Heat is released Temp goes up H is negative Entropy – level of disorder phase changes heating curve

Catalyst -- speeds up a reaction -- is not used up -- lowers activation energy

Endothermic Heat is absorbed Temp goes down H is positive

Specific heat - the amount of energy needed to raise one gram of a substance one degree Celsius H = m c ∆T specific heat of water = 1 cal/goC How many joules are absorbed when 35g of Al changes from 32oC to 46oC? The specific heat of aluminum is 0.89 J/goC.

How many calories are required to raise the temperature of 250 g of water from 50.0oC to 80oC?

What is the amount of heat required to raise 140 g of water from J

o

o

25 C to 75 C? Specific heat of water is 4.184

g

o

C

Heat of vaporization/fusion Problems 1) check units 2) multiply to get units to cancel out 1) If the heat of vaporization of water is 2261 J/g, what is the amount of heat energy required to change 32g of water at 100oC to 32g of water vapor at 100oC? 2) The heat of fusion of water is 80 cal/g. How much energy must be removed to turn 7.0g of water at 0oC into 7.0g of ice at 0oC? PreIB: 3) The heat of fusion of water is 6012 J/mol. How much energy must be removed to turn 14.5g of water at 0oC into ice at 0oC?

Chemistry SOL Notes #8 Volume =

1 cm3 = mL

1000 mL = L

1 dm3 = L

Kelvin = oC + 273 Boyle’s Law – P1V1 = P2V2

 inverse relationship

A balloon starts off with a volume of 8.0 L and a pressure of 12 atm. What will be the new volume if the pressure is increased to 348 atm? Charles’ Law –

V1 = V2 T1 T2

 direct relationship  temperature must be in Kelvin

A car tire has a volume of 15 L at a temperature of 22oC. What will be the new volume in liters if the temperature increases to 34oC? Combined Gas Law – (PreIB only)

P1V1 = P1V2 T1 T2

Ideal Gas Law – PV = nRT  Units: L, mol, K  R= “gas law constant”  will be given to you

A sample of 6.21 mol nitrogen gas (N2) occupies a balloon at a temperature of 53oC and pressure of 149 kPa. What is the volume of the balloon in dm3? Dalton’s Law of partial pressures = P1 + P2 + P3 + … A tank contains N2 at 1.4 atm and O2 at 2.2 atom. Helium is added to this tank until the total pressure is 5.9 atm. What is the partial pressure of the helium? What partial pressure of oxygen is a scuba diver breathing if the total pressure is 5.8 atm and 34% of the air is oxygen?