Download Unit 3 Spiraling

Chemistry Unit 3- Essential Knowledge
Unit 3 Problem Sets
(Answers for all problems, additional practice worksheets and a practice test are all eventually posted on Blackboard)
Instructions: Do Problems as Assigned. They must be done on a separate sheet of paper in PENCIL. Your full name (first and last),
the date, and your class period must be in the upper right corner of your paper. Answers to assigned problems must be legibly printed
(no cursive). Typing is only permitted with special permission.
SHOWING YOUR WORK IS REQUIRED FOR ALL MATH PROBLEMS!!!!!!!!
At the end of every problem set you must write in ink the honor pledge: “On my honor as a W-L student, I have neither given nor
received aid on this assignment.” And sign your name.
Failure to follow this procedure will result in your paper being returned to you with no credit given.
Topic
Essential Knowledge
Elements and the
Periodic Table
-There are only certain regions in the electron cloud where electrons are likely to be found. These regions are called
energy levels. The lowest energy level is closest to the nucleus; the highest energy level is farthest away from the
nucleus. Electrons will occupy the lowest available energy level(s) before they fill in higher levels.
-The outermost electrons in an atom are called valence electrons. The period (row) number on the periodic table
corresponds to the highest energy level occupied by the valence electrons in an element.
-Elements in the same group (column) on the periodic table have the same number of valence electrons. All of the
group 1 elements have one valence electron and group two elements have two. Group 13 elements have three valence
electrons, group 14 elements have 4, group 15 have 5 and so on through group 18 elements, which have eight valence
electrons.
-An ion is an atom that has a charge because it has gained or lost electrons. Positive ions (cations) have lost electrons;
negative ions (anions) have gained electrons. The amount of charge is equal to the number of electrons lost or gained.
-Max Planck discovered that atoms in a flame could absorb or emit energy in discrete amounts. This ‘discrete’
amount of energy is called a quantum. An atom is said to be in the ground state when all of its electrons are in the
lowest available energy levels. When an electron absorbs energy, it jumps to a higher energy level, and is said to be in
an excited state. When the excited electrons return to their ground state, they release the energy in the form of
electromagnetic radiation (light).
-Niels Bohr developed the planetary model using electron orbitals to explain the existence of the discrete lines in
an atoms emission spectra. The wavelengths of light represent the specific energies (distances from the nucleus) of
electrons in an atom. Though Bohr’s planetary model is used to explain the energy levels of electrons it is not an
accurate model, instead the Quantum Mechanical Model of a ‘fuzzier’ electron cloud model is the preferred model.
Werner Heisenberg’s uncertainty principle states that we cannot simultaneously know exactly where an electron is
and exactly how it is moving. We can only know one or the other, because the act of measuring interferes with the
particle we are trying to measure.
1.3
Problem Set 1.3
Read Chapter 5 pp.138-148
1. How are wavelength and frequency of light related?
2. Describe the cause of atomic emission spectrum of an element?
3. How is the change in electron energy related to the frequency of light emitted in atomic transitions?
4. How does quantum mechanics differ from classical mechanics?
Read Chapter 6 pp.158 -160
5. What are the three classes of elements found on the periodic table?
6. What type of elements tend to be good conductors of heat and electric current?
7. Identify each of the following as a metal, nonmetal or metalloid (semi metal)?
a. Gold b. sulfur c. silicon d. barium
Read Chapter 7 pp.187-193
8. What are valence electrons?
9. How do you determine the number of valence electrons in an element?
10. What is the octet rule?
11. How is a cation formed? What class of elements (metals, non metals or metalloids) tends to form cations?
12. How is an anion formed? What class of elements (metals, non metals or metalloids) tends to form anions?
13. How many valence electrons in:
a. Carbon
b. oxygen
c. magnesium
d. sodium
14. Draw the Bohr Model of the atom for Calcium and Silicon.
15. Complete the Following: Electrons in an atom occupy the ___ energy levels before they can occupy ___energy
levels. When electrons fill energy levels in the proper order, the electrons are in the ___ state. Metal atoms tend to
(lose/gain) ___ electrons when they react, forming (positive/negative) ____ions called _____. Nonmetal atoms tend to
____ electrons when they react, forming ___ ions called ___.
16. Make a table that includes Period #, Group #, Group Name, # of Valence Electrons, Number of Electrons Lost or
Gained, and Common Ion Charge for Li, Na, Mg, F, I and Ne
Compounds and
Bonding
2.3
-Elements in groups 1,2 and 13 (metals) will lose electrons and form positive ions (cations).
-Elements in Group 1 are called the Alkali Metals and Group 2 is called the Alkaline Earth Metals
-Elements in groups 15, 16 and 17 (nonmetals) will gain electrons and form negative ions (anions).
-Group 17 is called the Halogens and Group 18 is called the Nobel Gases.
-Ionic compounds are formed by the attraction between positive and negative ions. The charges must be balanced,
resulting in a compound with no net charge.
-When naming ionic compounds formed between group 1& 2 metals and group 15-17 nonmetals, the metal is written
first followed by the nonmetal with its ending changed to “ide” (Ex: MgO, magnesium oxide.)
Problem Set 2.3
Kinetic Theory
3.3
1. Complete a table with the following information for each of the ions listed: Al3+ Li1+ Mg2+ Br1- O2- N3Period #, Group Name, Metal or Nonmetal, # of Valence Electrons, # of Electrons Lost of Gained, Cation or Anion
2. Complete a table for the following Ionic Compounds in your Problem Set Work.
Name
Metal ion
Nonmetal ion
Chemical formula
Cesium oxide
Cs1+
O2Cs2O
Calcium bromide
Al2S
K1+
N3Aluminum fluoride
SrO
Ba2+
F1Magnesium Oxide
Na1+
S2AlP
Stronium Nitride
-Phase changes that require heat (like melting or boiling) are endothermic.
ΔH is positive for an endothermic change. This means heat goes in.
-Phase changes that give off heat (like freezing and condensing) are exothermic.
ΔH is negative for an exothermic change. This means heat is released.
-The amount of heat needed to melt a specific amount of a solid is called the heat of fusion.
-The amount of heat needed to boil a specific amount of a liquid is called the heat of vaporization.
-To calculate the total heat required to complete a phase change multiply the heat of fusion,
 Hf, times the total mass when melting. For boiling, multiply the heat of vaporization,  Hv.
Melting: Heat = mass x  Hf
Boiling:
Heat = mass x  Hv
Problem Set 3.3
1.
a)
b)
c)
d)
What physical change has occurred? _________________
Does particle motioC n speed up or slow down during the change? ___________
Does this change require or release energy? __________________
Is the change endothermic or exothermic?
2.
The Mole and
Stoichiometry
4.3
a) What physical change has occurred? _________________
b) Does particle motion speed up or slow down during the change? ___________
c) Does this change require or release energy? __________________
d) Is the change endothermic or exothermic?
3. Define Heat of Fusion.
4.Define Heat of Vaporization.
5. Calculate the energy required to melt 8.5 grams of ice at 0 o C. The molar heat of fusion is 6.02 kJ/mole
6. Calculate the energy required to boil 131 grams of water at 100oC to steam. The molar heat of vaporization is 40.6
kJ/mol.
-The molar mass of a compound is the sum of the molar masses of the individual elements in the compound.
-The percent by mass of an element in a compound can be determined:
% by mass of element = total mass of element in compound X 100
total mass of the compound
Problem Set 4.3
Chemical
Reactions
5.3
1) How many moles are in 25 grams of water?
2) How many grams are in 4.5 moles of Li2O?
3) How many molecules are in 23 moles of oxygen?
4) How many moles are in 3.4 x 1023 molecules of H2SO4?
5) How many molecules are in 25 grams of NH3?
6) How many grams are in 8.2 x 1022 molecules of N2I6?
7) What is the percent carbon in Glucose, C6H12O6?
8) How much carbon by weight in 360 grams of Glucose?
9)Determine the molar mass of each of these compounds
a) (NH4)2CO3 b) C6H12O6 c) Fe3(PO4)2
d) (NH4)2S
e)Zn(C2H3O2)2
-A chemical equation is a record of what happens in a chemical reaction. It shows the formulas of all the reactants
on the left hand side of the arrow, and the formulas for all the products on the right hand side.
-A balanced chemical equation has the same number of atoms of each element on either side of the arrow. When
balanced, the coefficients show the number of moles (mole ratio) of each substance that are required for a complete
reaction.
Problem Set 5.3
Balance the following Equations:
1.
_____ CO (g)
+ _____ O2 (g)  _____ CO2 (g)
2.
_____ Ca (s)
+_____ HCl (l)
 _____ CaCl2 (s) + _____ H2(g)
3.
_____ S (s)
+_____ O2 (g)
 _____ SO3 (g)
4.
_____ H2 (g)
+_____ Br2 (l)
 _____ HBr (g)
5.
_____ H2O (l) + _____ Fe (s)
 _____ Fe3O4 (s) + _____ H2(g)
6.
_____ CH4 (g) + _____ O2 (g)
_____ CO2 (g) + _____ H2O (g)
7.
_____ C2H6 (s) + _____ O2 (g)
_____ CO2 (g) + _____ H2O (g)
8.
_____ CuCl2 (s) + _____ Al (s)
 _____ AlCl3
+ _____ Cu (s)
Al(NO3)3 + FeCl2
Fe(NO3)2 + AlCl3
9. Write the formulas of the reactants in the above equation
10. Write the formulas of the products in the above equation
11. What would the coefficient of Al(NO3)3 be in the balanced equation?
12. What would the coefficient of Fe(NO3)2 be in the balanced equation?
13. What would the coefficient of AlCl3 be in the balanced equation?
14. How many oxygen atoms would there be on each side of the balanced equation?
15. How is balancing a chemical reaction related to the law of conservation of matter?
Balance the following Equations:
16.
___ NaNO3 + ___ PbO  ___ Pb(NO3)2 + ___ Na2O
17.
___ AgI + ___ Fe2(CO3)3  ___ FeI3 + ___ Ag2CO3
18.
___ C2H4O2 + ___ O2  ___ CO2 + ___ H2O
19.
___ ZnSO4 + ___ Li2CO3  ___ ZnCO3 + ___ Li2SO4
20.
Solutions
6.3
___ V2O5 + ___ CaS  ___ CaO + ___ V2S
-Solubility is defined as the amount of solute that will dissolve in 100 g of solvent.
-Dissolving is a physical change.
Example: C12H22O11 (s)  C12H22O11(aq)
-Dissociation occurs when ionic substances dissolve. Dissociation can be represented by an equation. Dissociation is
also a physical change.
Example: NaCl(s)  Na+(aq) + Cl-(aq)
-If a solution gets colder when a solute dissociates, it is an endothermic change and ΔH is positive, and heat is
written to the left of the arrow.
NH4NO3(s) + heat  NH4+(aq) + NO3-(aq)
-If a solution gets warmer when a solute dissociates, it is an exothermic change and ΔH is negative, and heat is
written to the right of the arrow.
CaCl2 (s)  Ca2+ (aq) + 2 Cl- (aq) + heat
Problem Set 6.3
Experimentation
7.3
Read Pages 471-473. On pg 474 do Intrepreting Graphs Questions a, b, and c. Questions 3 and 4 on page 477
(Section Assessment) Questions 42, 43, 44, 47 on Page 499 (Reviewing Content)
-Oxidation is the loss of electrons. When an electron is removed from a neutral atom it becomes a cation. It is
positively charged and has an increase in its oxidation state. In the form of a chemical reaction, removing an electron
from lithium is written as
Li0  Li+ + eLi+ is called the lithium ion
-Reduction is the gain of electrons. When an electron is added to a neutral atom it becomes an anion. It is negatively
charged and has a decrease in its oxidation state. In the form of a chemical reaction, adding an electron to fluorine is
written as
F0 + e-  F –
F – is called the flouride ion
Problem Set 7.3
Read Pages 631-634 on page 634 Practice Problems 1 and 2.
Review
This is your first attempt to show understanding of the unit concepts. You must show competency for each & every unit concept to be
eligible for a passing mark at the end of the Unit.
1. How many valence electrons does each of the following atoms have?
Neon _________________
Aluminum ________________
1.3
Iodine __________________
2. What element has 17 protons and 15 neutrons in the nucleus?
3.
How does a nitrogen atom (N) become a nitride ion (N3-)?
4.
How many does an aluminum ion (25Al3+) have?
Protons _________________
Neutrons ________________
Electrons __________________
Write the correct formula for aluminum phosphide by balancing the charges. Show how you do this.
1.3 and 2.3
1.1,1.2 and 1.3
5.
2.3
6. Ionic bonds form between _______________ and _________________.
3.1 and 3.2
7. Is melting exothermic or endothermic? Explain.
3.3
8. What is the molar mass of Al2(SO4)
4.3
6.
What is the percentage by mass of aluminum in Al2(SO4)?
7.
A student has a sample of calcium chloride that weighs 16 grams. How many moles of calcium chloride does the
student have?
8.
How many molecules of calcium chloride does the student have?
9.
What is the difference between oxygen-18 and oxygen-19? BE SPECIFIC.
4.3
4.2 and 4.3
4.1
4.2
10. Identify the products and the reactants in the following equation. Also give the state of matter for each
substance.
2CO (g) + energy  2C (s) + O2 (g)
5.3
5.3
5.1 and 5.2
11. What is the mole ratio of solid carbon to oxygen gas in this reaction?
2CO (g) + energy  2C (s) + O2 (g)
12. Does the following equation represent a physical change or a chemical change? Explain how you know.
2H2O (l) + energy  2H2 (g) + O2 (g)
Give the reaction type: ________________
The decomposition of water using electricity is called___________________.
13. Does the preceding equation represent an endothermic or an exothermic change? Explain.
5.3
14. Is an unsaturated solution of NaCl and water a heterogeneous or a homogeneous mixture? Explain.
SOLUTE: ____________
SOLVENT: __________
6.1 and 6.2
6.3
7.1, 7.2 and 7.3
15. Which of the following equations correctly represents the exothermic dissociation of CaCl2 in water? Explain.
a) Ca+2 (aq) + 2Cl-(aq)  CaCl2 (s) + heat
b) Ca+2 (aq) + 2Cl-(aq) + heat  CaCl2 (s)
c) CaCl2 (s)  Ca+2(aq) + 2Cl-(aq) + heat
d) CaCl2 (s) + heat  Ca+2 (aq) + 2Cl-(aq)
16. Draw a model to represent aqueous chloride ions. REMEMBER THE MODEL FOR THE DISSOCIATION
LAB!