Final Exam Review-- KEY
Atomic Theory &Structure
1) Explain the differences in the atomic theories of Democritus, Dalton, Thomson, Rutherford and Bohr.
We cannot know the exact place an electron is in. Uses probability clouds where it is MOST LIKELY.
2) Explain how the modern atomic theory is different from all of these.
We cannot know the exact place an electron is in. Uses probability clouds where it is MOST LIKELY.
3) Name each of the 4 quantum numbers and tell what information they give about the location of the electrons.
FIRST NUMBER – energy level electron is in.
SECOND NUMBER – shape of electron cloud/orbital. (s, p, d, f)
THIRD NUMBER – orientation of that orbital in 3D space. (s has 1, p has 3, d has 5)
FOURTH NUMBER – if the electron spins up or down.
4) What can you tell about the ELECTRONS in an element if the last orbital is 4d6?
These electrons are in the 4th main energy level. They are in double-peanut shaped
orbitals. There are six electrons. 4 of them are unpaired and spinning in the same
direction. Two electrons are paired and spinning in opposite directions.
5) List each of the three principles used in writing electron configurations and what they state.
AUFBAU’S PRINCIPLE - states that the lowest energy levels will be filled first
PAULI EXCLUSION PRINCIPLE states that electrons are always paired and each suborbital (orientation) can only hold two electrons.
HUND’S RULE - states that electrons will remain unpaired in each suborbital until they have to start pairing up (all ups, then all downs)
6) Explain what a line emission spectrum is and why they are unique for each element.
Line emission spectrum are created when electrons in an atom absorb energy. This allows them to ‘jump’ up energy levels. This is called the excited state. As the electrons drop back down to their original energy level (ground state) they release this energy as colored light. The energy between the main energy levels and orbitals is quantized, or a specific amount. Each color can be ‘read’ as a specific amount of energy. Because every element has a unique electron configuration, its emission spectrum will be unique as well.
7) Complete the table below, indicating whether each trend increases or decreases from top to bottom of the periodic table and from left to right.
PERIODIC TRENDS: / From Top to Bottom of PT / From Left to Right of PTAtomic Size / Increases / Decreases
Ionic Size / Increases / Decreases
Electronegativity / Decreases / Increases
Electron Affinity / Decreases / Increases
Ionization Energy / Decreases / Increases
8) List three properties of metals:
- conduct electricity, malleable, ductile, high luster, form cations
9) For each of the following elements give AND LABEL: electron configuration, orbital configuration, noble gas configuration and Lewis Dot Structure (If applicable!):
a. Magnesium - 1s22s22p63s2 [Ne]3s2 ¯ Mg:
b. Iron - 1s22s22p63s23p64s23d6 [Ar]4s23d6 ¯ ¯ ¯ ¯ ¯ No lewis struct.
c. Selenium - 1s22s22p63s23p64s23d104p4 [Ar] 4s23d104p4 ¯ ¯ ¯ Se (6 dots)
d. Rubidium - 1s22s22p63s23p64s23d104p65s1 [Kr]5s1 Rb.
10) Complete the following table:
Symbol
/ Atomic # / Mass # / # protons / # electrons / # neutrons / Physicist’s Notation / Hyphen-NotationSi / 14 / 29 / 14 / 14 / 15 / 2914Si / Silicon-29
Li / 3 / 7 / 3 / 3 / 4 / 73Li / Lithium-7
Mg / 12 / 25 / 12 / 12 / 13 / 2512Mg / Magnesium-25
C / 6 / 12 / 6 / 6 / 6 / 126C / Carbon-12
C / 6 / 14 / 6 / 6 / 8 / 146C / Carbon-14
Compositional Stoich and Naming
1) Rubidium has two common isotopes, Rb and Rb. If the abundance of Rb-85 is 72.2% and the abundance of Rb-87 is 27.8%, what is the average atomic mass of rubidium? 85.56 g/mol
2) Uranium has three common isotopes. If the abundance of uranium-234 is 0.01%, the abundance of uranium-235 is 0.71%, and the abundance of uranium-238 is 99.28%, what is the average atomic mass of uranium? 237.98 g/mol
3) Titanium has five common isotopes: titanium-46 (8.0%), titanium-47 (7.8%), titanium-48 (73.4%), titanium-49 (5.5%), titanium-50 (5.3%). What is the average atomic mass of titanium? 47.92 g/mol
4) Explain why atoms have different isotopes. In other words, how is it that helium can exist in three different forms? The number of neutrons can be changed WITHOUT changing the element’s identity. Neutrons exist to stabilize the nucleus – without them, the nucleus would consist of nothing but positively-charged protons in close proximity to one another. Because there are different ways of stabilizing the protons, there are different isotopes.
5) Write the percent composition for:
a. manganese (III) nitrate - % Mn 22.8 % N 17.4 % O 59.8
b. lithium phosphide - % Li 40.0 % P 60.0
6) What’s the empirical formula of a molecule containing 65.5% carbon, 5.5% hydrogen, and 29.0% oxygen? C3H3O
7) If the molar mass of the compound in problem 6 is 110 grams/mole, what’s the molecular formula?
C6H6O2
8) What’s the empirical formula of a molecule containing 18.7% lithium, 16.3% carbon, and 65.0% oxygen?
Li2CO3
9) If the molar mass of the compound in problem 8 is 73.8 grams/mole, what’s the molecular formula?
Li2CO3
10) How many moles are present in 34 grams of Cu(OH)2? 0.35 moles
11) How many moles are present in 2.45 x 1023 molecules of CH4? 0.41 moles
12) How many grams are there in 3.4 x 1024molecules of NH3? 96 grams
13) How much does 4.2 moles of Ca(NO3)2 weigh? 689 grams
14) Describe the difference between ionic, covalent and metallic bonds. In an ionic bond, one atom loses electrons to become positively charged and one gains those same lost electrons to become negatively charged. Their opposite charges attract and keep the compound bound. In a covalent bond, the electrons are shared between two atoms so that both have a complete set of 8 valence electrons. Metallic bonds have a ‘sea of electrons’
15) Explain polarity. One end of the molecule has more of the shared electrons, giving it a slight negative charge. The other end is lacking more of the electrons and has a slight positive charge.
j. PBr - phosphorous monobromide
k. OBr2 - oxygen dibromide
l. Ca3(PO4)2 - calcium phosphate
m. NH4I - ammonium idodide
n. Mn(NO3)3 - manganese (III) nitrate
o. FePO4 - iron (III) phosphate
p. CoCO3 - cobalt (II) carbonate
Rxn Chemistry
1) Equations: (write and balance these first before moving to the questions below)
a) In a decomposition reaction, aluminum oxide and carbon dioxide are products are formed from the break down of aluminum carbonate.
Al2(CO3)3 à Al2O3 + 3 CO2
b) If ammonia (NH3) and oxygen gas are combined nitrogen monoxide and water are usually formed.
4 NH3 + 5 O2 à 4 NO + 6 H2O
c) Oxygen and copper(I) sulfide are heated to produce copper(I) oxide and sulfur dioxide in a very stinky reaction.
3 O2 + 2 Cu2S à 2 Cu2O + 2 SO2
d) In a double replacement reaction, sodium carbonate and calcium phosphate are produced when calcium carbonate and sodium phosphate are reacted.
3 CaCO3 + 2 Na3PO4 à 3 Na2CO3 + Ca3(PO4)2
e) Iron metal is produced by the reaction of iron(III) oxide and carbon monoxide. Carbon dioxide
is the other product in the reaction.
Fe2O3 + 3CO à 2 Fe + 3 CO2
2) Reaction Stoichiometry: (You must choose which equation to use from #7.)
a) Calculate the number of moles of sulfur dioxide that are produced when 46.25 grams of oxygen reacts.
0.9635 mol Cu2S (rxn C)
b) If a student decomposes 9.750 grams of aluminum carbonate and she collects the gas and measures 4.6130 grams of carbon dioxide, determine the percent yield for this reaction.
83.87% (rxn A)
c) How many moles of each product is produced when 3.25 moles of oxygen reacts with an excess of ammonia?
2.6 mol NO, 3.9 mol H2O (rxn B)
d) Calculate the mass of calcium carbonate needed to react with 1.920 moles of sodium phosphate.
288.3g CaCO3 (rxn D)
e) Calculate the percent yield when 42 .8 grams of iron(III) oxide reacts with an excess of carbon
monoxide and 29.092 grams of iron is produced.
97.2% (rxn E)
f) How many moles of water are produced when 4.3 mol ammonia and 2.5 mol oxygen gas react? How much excess reagent remains?
3.0 mol H2O; 2.3 mol excess NH3 (rxn B)
Properties of Matter
1) A hot dog is cooked
· Chemical or physical change? Cooking is generally thought of as being a chemical change.
· Your reason: The properties of the hot dog (consistency, taste, etc) are different after cooking than before, suggesting that drastic changes have been made.
2) Thousand Island dressing and mayonnaise are mixed to make “secret sauce” for hamburgers
· Chemical or physical change? Physical change
· Your reason: Mixing things doesn’t break or make chemical bonds
3) Water is boiled in preparation for making pasta
· Chemical or physical change? Physical change
· Your reason: The process of boiling doesn’t break the bonds in water molecules
4) A rock star gets a tattoo on his forehead
· Chemical or physical change? Physical change
· Your reason: The dye in tattooing ink doesn’t formally bond to the skin. - Reversible
5) Explain the difference in the particles in each state of matter in regards to their energy, distance from each other, and attraction to each other. Gas – particles have high energy, move fast, far apart, low attraction. Liquid – particles have medium energy, close together but moving, some attraction. Solid – low energy, tightly packed, high attraction.
6) List two chemical and two physical properties that would distinguish water from motor oil. CHEMICAL – oil is flammable, water and sodium react. Any reactions. PHYSICAL – color, smell, taste (ew!), thickness
7) Draw a phase change graph and label the different parts (solid heating, melting, liquid heating, etc) See notes in your notebook
Solution Chemistry
16) List the properties of acids. sour taste, corrosive, H+ ions, pH < 7, electrolyte, red litmus, neutralizes a bases
17) List the properties of bases. How are they different than acids? bitter taste, slippery, caustic, blue litmus, pH > 7, electrolyte, neutralizes an acid
18) What is ionization? when an ionic compound breaks down into its ions in water.
19) What is pH? How does it relate to concentration of hydrogen ions? pH is a measure of the acidity of a substance. pH = -(log [H+])
20) What is monoprotic, diprotic and triprotic in relation to acids? a monoprotic acid produces one H+ when it ionizes. A diprotic produces two and a triprotic produces 3.
21) Give the basic rules for naming binary and ternary acids. Binary Acid - add prefix hydro-, change ending to -ic. Ternary - no prefix, change -ate to -ic and -ite to -ous.
22) Complete the chart.
Theory/example
/ Acid / BaseARRHENIUS
/ Produces H+, H3O+(hydrogen and hydronium ions / Produces OH- (hydroxide ions)
example / HCl / KOH
BRONSTED-LOWRY / Proton donator / Proton acceptor
example / H2SO4 / NH3
23) Write the names for the following acids and bases:
a. KOH - potassium hydroxide
b. H2Se - hydroselenic acid
c. HC2H3O2 - acetic acid
d. Fe(OH)2 - iron (II) hydroxide
24) What is the difference between hydrosulfuric acid, sulfuric acid and sulfurous acid? Hydrosulfuric acid is a binary acid, containing hydrogen and sulfide (H2S). Sulfuric is a ternary acid containing hydrogen and sulfate (H2SO4). Sulfurous is a ternary acid containing hydrogen and sulfite (H2SO3).
25) If a solution has a [H+] concentration of 1.4 x 10-3, what is the pH? and the pOH? pH = 2.85, pOH = 11.15
26) If a solution has a pOH of 13.4, what is the [H+]? Is it an acid or a base? pH = 0.6, [H+] = 0.25 M - Acid
27) What is the hydroxide concentration of the following solutions:
a. pH = 3.4 - pOH = 10.6, [OH-] = 2.5 x 10-11
b. pOH = 3.0 - [OH-] = 1 x 10-3
c. pOH = 9.2 - [OH-] = 6.3 x 10-10
28) What is the pH of a solution that contains 2.4 x 10-5 moles of hydrobromic acid in 0.5 L of water? First you have to calculate the [H+] concentration, which will be the same as the [HBr]. M = moles solute/ L solution. M = 4.8 x 10-5 (also the [HBr]). [H+] = 4.8 x 10-5 M, pH = 4.3
29) What is the molarity of a solution that has 450 grams of sodium chloride in 800 mL of water? 450 g NaCl = 7.69 mol NaCl, M = 9.62 mol/L
30) What is the molarity of a solution that contains 100 grams of iron (II) nitrate in 2.4 L of water? 100 g Fe(NO3)2 = 0.60 mol Fe(NO3)2, M = 0.25 mol/L
31) How would you prepare a 3.2 M solution of KOH in a 500 mL volumetric flask? to make the solution you have to weigh out 1.6 mol KOH = 89.6 g KOH, then you would dilute that amount to the 500 mL mark on the flask.
32) How would you dilute your 3.2 M solution to 250 mL of a 1.2 M solution? M1V1 = M2V2, You would transfer 93.8 mL of the original solution to a 250 mL flask and dilute.
33) What is the difference between ionic and covalent bonds? Covalent compounds share electrons. Ionic compounds transfer electrons (one gives/one takes, positive and negative charges formed)
34) In the following equations, label the acid, base, conjugate acid and conjugate base:
a. HCO3- + NH3 à CO3-2 + NH4+
A B CB CA
b. H3PO4 + OH- à H2O + H2PO4-
A B CA CB
c. H2O + HPO4-2 à PO4-3 + H3O+
B A CB CA
d. HCO3- + NH3 à CO3-2 + NH4+
A B CB CA