chemistry unit 0 test 2

# protons =

# of electrons

block d

(block f on picture) lanthanides

block b

(d block) transition metals

% error formula

(exact value - approximation/exact value) X 100

blocks a and c

(s and p on picture) the main groups

Proton mass and charge

1 amu ≈ 1 gram/mole charge is +1

Neutron mass and charge

1 amu ≈ 1 gram/mole charge is neutral

Electron mass and charge

1/2000 of a g/mole charge is negative

ex. how many H atoms in 36 g H2O?

? H atoms= 36 g H2O (1 mole H2O/18g)(2 mole H atoms/1 mole H2O)(6x10^23 atom/mole)= 2x2x6x10^23= 24x10^23 H atoms

ex. how many g O atoms in 6*10^23 molecules C3H8O?

? g O atoms= (6*10^23)(1 mole C3H8O/6*10^23)(1 mole O atom/ 1 mole C3H8O)(6*10^23 atom/ 1 mole O) = 16 g O atoms

direct proportional function

A = abc A ∝ C (1,2) (2,4) (3,6)

valence electrons in CCl4

C = 4 electrons are valence electrons Cl = 7 electrons are valence electrons so the total valence electron is 4 + (7 x 4) = 32 e-

Given 2H2+O2 --> 2H2O, 6g of H2 reacts with excess O2 to make 9 grams of H2O. What is the percent yield?

Find the number of grams of H2O: g H2O = 6 g H2 (1 mole H2/ 2g H2)(2 mole H2O/ 2 mole H2)(18 g H2O/ 1 mole H2O) = 6*2*18/2*2 = 3*18 = 54 g H2O theoretically The actual is 9 g H2O/ 54 g H2O = 1/6 or 16% yield

alkali metals

Group 1

alkaline earth metals

Group 2

halogens

Group 7A

noble gases

Group 8A

Displacement reactions are oxidation reduction reactions

Know that these reactions involve H2O and metals. Na + H2O --> Na+ + H2 + OH- (Na+ =salt, H2= explodes, OH- = base) Ag + H2O --> no reaction (coinage metals do not react)

Calculate dilution

MbVb=MaVa or M1V1=M2V2

solubility reactions or ionic reactions

NaCl(aq) + AgNO3(aq) -->AgCl(s) + NaNO3 Or net ionic Ag+(aq) + Cl-(aq) --> AgCl(s) These reactions always involve ionic compounds from opposite sides of the periodic table.

Given 2H2+O2 --> 2H2O, find the limiting reagent. Start with 4 grams of H2 and 16 grams of O2.

Now, convert mass to moles: H2 is 4g/2g/mol=2 moles O2 is 16g/32g/mol=0.5 moles Since it takes 1 mole of O2 to react with 2 moles of H2, you run out of O2 first so you use O2 in calculation of products.

inverse proportional

PV=nRT P ∝ 1/v as P goes up, V will go down (1,1) (1, 1/2) (3, 1/3)

Phase/physical reactions

Phase changes like freezing. These are physical changes. Not chemical. CO2(s) --> CO2(g) H2O(l) --> H2O(s)

quadratic or parabola (power function)

Rate = k[A]^2 As [A] increases rate increases as a rough square. (1,1) (2,4) (3,9)

Perform an empirical formula calculation.

Step 1. Assign grams (out of 100) to each element in the molecule. Step 2. Divide each assigned grams by molar mass to get moles. Step 3. Ratio each element to the smallest element. Step 4. Create the empirical formula with integer results. All elemental subscripts must be integers (no fractions) with simplest ratios.

acid-base reaction

These are ionic but involve acids and bases in some form. Look for H+ on the first compound and look for an OH-on another compound. HCOOH + NaOH-->Na+ + COOH- + H2O HNO3 +NaOH-->Na+ + NO3- +H2O

How to find neutrons

atomic mass - atomic number

protons function

atomic number and is what determines the type of element

electrons function

balances charge of proton, also the key particle that creates chemical reactions to make different kinds of matter.

neutrons function

determines the isotope of an element 1H vs 2H vs 3H has 1 proton with 0, 1, and 2 neutrons

average number convert # to moles

ex. 1 mole of H2O is 6*10^23 molecules ex. 1 mole of C3H8O is 6*10^23 molecules

molar mass to convert g to moles

ex. H2O is 18grams/ 1 mole ex. C3H8O is 60 grams/ 1 mole

mole atoms to moles of molecules

ex. H2O: 2 moles of H atoms/ 1 mole of H2O ex. C3H8O: 3 moles of C atoms/ 1 mole of C3H8O

columns=

groups/family

combustion reaction

involve oxygen burning an organic molecule to make CO2 and H2O. 2 H2 + O2 --> 2 H2O CH4 + 2 O2 --> CO2 + H2O

Given a molecular formula, convert to percent composition by mass.

mass of atom(s)/mass of molecule x 100

MKS units

meters (m), kilograms (kg), seconds (s)

Given an empirical formula and molar mass of a compound, find the molecular formula.

molar mass of the compound/ molar mass of the empirical formula = simple integer multiply that integer x empirical formula

rows =

periods

inverse square

v= R(1/n1^2 - 1/n2^2) As n goes up, v decreases as a rough inverse square (1,1) (2, 1/4) (3, 1/9)

exponential

y=2^x (1,1) (2,4) (3,8) (4,16) -y

logarithmic

y=lnx (1,0) (2,0.7) (3,1.1)