Scholarship Science 9- First Semester Exam 2014-2015 KEY
What will your exam consist of?
o 100 multiple choice questions over course content & laboratory assignments
o Problems on atomic structure, equation balancing, formula mass calculation, formula writing ion formation
and drawing structural formulas
What can you
o
o
o
bring to your exam?
Pencils
Calculator
Prepared 3 X 5 notecard
 Must be handwritten
 Both sides can be used
 You may put anything you want on this sheet.
Atomic structure
Textbook question:
Pg. 330 Review #2,5,8,9,10,13
2. Atoms bumping into the particles
5. The atomic nucleus
8. The periodic table has 7 periods.
9. The periodic table has 18 groups.
10. Across any period, the properties of elements gradually change.
13. Protons have a +1 charge and neutrons have a 0 charge.
Pg. 331 Review #14, 15, 16, 18, 19;
14. Tow atoms are isotopes of each other when they have the same number of protons but a different number of
neutrons.
15. Atomic number is the number of protons in the nucleus. Mass number is the total number of protons and neutrons in
the nucleus.
16. Mass number is the count of protons and neutrons in the nucleus of an isotope. Atomic mass is a measure of the total
mass of an atom.
18. Seven
19. The electrons in the outermost shell of an atom, called the valence electrons, are the ones most responsible for the
properties of an atom.
Pg. 331 Think and Compare #1, 2;
1. B, A, C. A given mass of carbon-13 has few atoms than the same mass of carbon-12 and uranium, which is very heavy,
has fewer still to equal 1 gram.
2. Li, Na, K (see pg 322 Fig 15.10)
Pg. 331 Think & Explain #7,8,9;
7. The remaining nucleus is that of Carbon-12.
8. The atomic mass would be 99 amu, and the element would be technetium, Tc, atomic number 43.
9. When an atom is neutral the number of protons equals the number of electrons so there would be 79 electrons.
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Pg. 332 Think & Explain #11,12,13,18,19,20;
11. The atomic masses listed in the periodic table are average numbers that reflect the variety of isotopes that exist for
an element.
12. Protons, which are nearly 2000 times more massive than electrons, contribute much more to the mass of an atom.
Protons, however, are held within the atomic nucleus, which is only a tiny fraction of the volume of the atom. The size of
the atom is determined by the electrons, which sweep through a relatively large volume of space surrounding the nucleus.
13. The diagram to the far right where the nucleus is not visible.
18. Golf balls are much heavier, so there are few per kilogram.
19. Oxygen atoms are heavier than carbon atoms, so there are fewer of them per kilogram
20. Lead is heavier than aluminum, so there are more atoms in 1 kg of aluminum
Pg. 332 RAT #5,8,9,10
5. d
8. a
9. b
10. b
A) Subatomic particles
a. What are the atomic mass units for protons, neutrons, and electrons? Protons and neutrons =1 amu,
electrons about 0 amu
What does the atomic number represent? # of protons
b. What does the mass number represent? # of protons + # of neutrons
c. What particles are in equal numbers in a neutral atom? Protons and electrons
d. How is the number of protons determined? From the atomic number
e. How is the number of neutrons determined? Mass # - # of protons
f. How is the number of electrons determined in a neutral atom? # protons = #electrons
g. What subatomic particles are located in the nucleus? Protons and neutrons
h. Complete the following diagrams and fill in the charts for each element. Use the periodic table as a
reference.
------------------------------------------------------------------------------------------------------------------
C) The electron cloud
a.
What determines the location of an electron in the electron cloud? How many energy levels are
present. Electrons fill the energy levels in order (2-8-8-18)
b.
How many electrons can be found in the first energy level of an atom? 2
2
c.
d.
How many electrons can be found in the second energy level of an atom? 8
How can the electron arrangement/configuration be determined for a neutral atom? In a neutral atom
the # of protons = # electrons then fill energy levels using the following arrangement 2-8-8-18
D) Isotopes
a. How are isotopes different from other forms of the same element? They have the same number of
protons but different number of electrons and mass number.
b.
Which pairs of atoms are isotopes of the same element?
i.
ii.
c.
and
122
50Sn
iii.
39
17Cl
iv.
121
50Sn
17
8O
and
and
122
52Te
39
19K
and
119
50Sn
Identify the most abundant isotope for each element.
i.
ii.
iii.
iv.
v.
vi.
vii.
d.
16
8O
Fe-54 Fe-56 Fe-57 Fe-58
O-16 O-17 O-18
Mg-24 Mg-25 Mg-26
S-32 S-33 S-34 S-36
Ar-36 Ar-38 Ar-40
Hg-196 Hg-198 Hg-199 Hg-202 Hg-204
Kr-78 Kr-80 Kr-82 Kr-83 Kr-84 Kr-86
What is the average atomic mass of element Z with the following isotopes: Z-34.967 with 75.78%
abundance and Z-36.965 with 24.22% abundance? What element is Z most likely to be?
Let X = average atomic mass of element Z
X = mZ-35(%)Z-35 + mZ-37(%)Z-37
X = 34.967(.7578) + 36.965(.2422)
X = 35.451 amu
The element is most likely chlorine.
e.
For the purpose of this question, gold will have two isotopes; Au-197 and Au-195. Determine the percent
abundance of Au-197. Please refer to your periodic table for the average atomic mass (aka: atomic
weight).
Let X = % abundance of Au-197
mavg = mAu-197(%)Au-197 + mAu-195(%)Au-195
196.97 = 197(X) + 195(1-X)
X = .985
Au-197 is 98.5% abundant.
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Periodic Table
Textbook Questions:
Pg. 380 Review Questions #4;
4. Molecules are made of atoms. Atoms link together to form larger but still small basic units of matter called molecules.
Pg. 381 Review Questions #5, 6, 9-13, 15-20;
5. The particles in a gas have so much energy that they overcome their attractions to one another and expand to fill all
of the space available. This explains hos gases occupy much more volume than do liquids and solids, whose particles are
adjacent to one another.
6. Freezing
9. Nothing. During a physical change, the chemical identity of a substance remains the same.
10. The electrical attraction that holds two atoms together.
11. The way the atoms are bonded together.
12. Both involve changes in appearance.
13. Iron and rust are two different materials. The transformation of one to the other, therefore, is considered a
chemical change.
15. Across any period, the properties of an element gradually change.
16. Atom refers to submicroscopic particles in a sample; element refers to microscopic and macroscopic samples.
17. An element has only one type of atom. A compound has combinations of different types of atoms.
18. The chemical formula tells us the ratio in which atoms come together to form a particular substance.
19. TiO2
20. They are more convenient.
Pg. 382 Think and Compare # 1,2;
1. In order of increasing speed: a frozen glacier, a flowing river, a steam-hot geyser
2. In order of increasing atomic size: oxygen, silver, cesium
Pg. 382 Think and Explain #4,8,9,10,12,16,18,19;
4. They evaporate into the gaseous phase, which is a physical change
8. The attractions among the submicroscopic particles of a material in its solid phase at 25°C are stronger than they are
within a material that is a gas at this temperature.
9. One gram of water vapor, the gaseous phase of water, occupies the most space.
10. The 50 mL plus 50 mL do not add up to 100 mL because within the mix, many of the smaller BBs can fit within the
pockets of space that were empty within the 50 mL of large BBs.
12. a) chemical, b) chemical, c) physical, d) chemical e) chemical, f) chemical g) physical
16. Water used to be classified as an element, but that was before people recognized that the basic building blocks of
matter are tiny particles called atoms. Today, an elements identified as a material consisting of only one kind of atom and
water has 2 different types of atoms.
18. H2S
19. Barium nitride
Pg. 382-383 RAT #1-5, 8, 10
1. d
2. a
3. d
4. d
5. c
8. b
10. d
4
A) Identifying elements by atomic number
a. Atomic # is the number of? protons
B) Identifying elements with the same number of valence electrons (which column?)-see first periodic table
below
a. Which elements have one valence electron? Group/Family 1
b. Which elements have two valence electrons? Group/Family 2
c. Which elements have three valence electrons? Group/Family 13
d. Which elements have four valence electrons? Group/Family 14
e. Which elements have five valence electrons? Group/Family 15
f. Which elements have six valence electrons? Group/Family 16
g. Which elements have seven valence electrons? Group/Family 17
h. Which elements have eight valence electrons? Group/Family 18
C) Identifying elements by family
a.
b.
c.
d.
Which
Which
Which
Which
elements
elements
elements
elements
are alkali metals? Group/Family 1
are alkaline earth metals? Group/Family 2
are halogens? Group/Family 17
are noble gases? Group/Family 18
D) Identifying elements by period (which row?)
a.
b.
c.
d.
e.
f.
g.
Which
Which
Which
Which
Which
Which
Which
elements
elements
elements
elements
elements
elements
elements
have one electron shell? Period 1
have two electron shells? Period 2
have three electron shells? Period 3
have four electron shells? Period 4
have five electron shells? Period 5
have six electron shells? Period 6
have seven electron shells? Period 7
E) Identifying elements by area of the periodic table
a. Which elements
b. Which elements
c. Which elements
d. Which elements
Periodic table
are metals? Blue
are nonmetals? Yellow
are metalloids? Pink
are transition metals? Purple/pink in top
Using the Periodic Table, give the following information for the element Nitrogen:
_____7______1. Number of protons
_____7______2. Number of neutrons
_____5______3. Number of valence electrons
_____2______4. Number of electron shells
___nonmetal__5. Metal or non-metal?
_____O______6. Symbol of the element with the next highest atomic number
_Group/Family 15_7. Name of the chemical family containing Nitrogen
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_P,As,Sb,Bi__8. Name of another element in the same family with Nitrogen
_Li,Be,B,C,O,F,Ne____9. Name of another element in the same period with Nitrogen
Ionic bonding
Textbook Questions:
Pg. 408 Review Questions #1-6, 10,11;
1. They have the same number of valence electrons.
2. 4
3. It gains electrons
4. Fluorine has room for only one more electron in its outmost shell.
5. The electrical force of attraction between oppositely charged ions.
6. Elements on opposite sides of the periodic table (metals and nonmetals).
10. The electronic charge on Ca is +2 in CaCl2.
11. Metals tend to lose electrons.
Pg. 409 Review Questions #13, 14;
13. Nonmetals
14. Two electrons are shared per covalent bond, so four are shared in a double covalent bond.
Pg. 410 Think and Explain #1-3, 5, 6
1. The number of unpaired valence electrons in an atom is the same as the number of bonds that the atom can form.
2. MgCl2
3. Potassium only has one valence electron so it will lose the single valence electron since the shell below is full making it
stable.
5. The valence electrons of a potassium atom are weakly held by the nucleus. The potassium atom has a hard enough time
holding on to its one valence electron, let alone a second one, which would happen if the potassium joined in a covalent
bond.
6. O with F Covalent; Ca with Cl ionic; Na with Na neither; U with Cl ionic
A) Electrons are transferred between atoms
B) Valence electrons- outer shell electrons
C) Metals
a. Lend valence electrons
b. 1 – 4 valence electrons
c. Form positive ions ( more protons than electrons)
D) Nonmetals
a. Borrow valence electrons
b. 4 - 8 valence electrons
c. Form negative ions (more electrons than protons)
E) Metals lend and non-metals borrow to become stable.
a. Stable- having only full outer electron shells
F) Oxidation number
a. The number of electrons an atom can lend, borrow, or share
b. Metals have positive oxidation numbers
1. Calcium has two outer shell electrons
2. Calcium lends two electrons
3. Calcium has an oxidation number of 2+
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c. Nonmetals have negative oxidation numbers
1. Oxygen has six outer shell electrons
2. Oxygen gains two electrons to have a full outer shell of 8
3. Oxygen has an oxidation number of 2d. There are no oxidation numbers above 4.
G) Electrolytes
a. Ionic compounds dissolved in water will conduct electricity
H) Draw the electron configuration for the following:
a. Potassium
c. Aluminum
b. Lithium
d. Carbon
I) Draw the ionic bonds between the following. Make sure to draw the Lewis Dot structures. Which ones are the
anions and cations:
a.
Sodium & Phosphorus
b.
Lithium & Chlorine
J) Draw the electron dot diagram (Lewis Dot Structure) and then tell if it would give up or take on electrons to get a
full shell. Also tell what charge it would have (positive or negative and how much ex: +2)
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Rules for formula writing
A) Metals are listed first
B) Nonmetals are listed second
C) The total number of electrons shown as being lost by the metal must equal the total number of electrons
shown being gained by the nonmetal.
D) The number 1 is NOT used as a subscript.
E) When the subscripts would be the same for both the metal and nonmetal they are not used.
F) If you are using a polyatomic ion use parentheses when you need more than one of that group
g) Examples
a. Calcium and Chlorine- CaCl2
b. Magnesium and oxygen- MgO
c. Magnesium and phosphorus- Mg3P2
d. Aluminum and hydroxide – Al(OH)3
G) Write the formulas for the following compounds.
1. Magnesium chloride ____MgCl2____________
4. Titanium(III) oxide ______Ti2O3________
2. Magnesium nitride _____Mg3N2____________
5. Ammonium sulfate _____(NH4)2SO4_________
3. Copper (II) nitride _____Cu3N2____________
6. Barium nitrate _____Ba(NO3)2_________
H) Write the correct formula for each of the following compounds.
1) Cesium fluoride (cesium & fluorine) CsF
4) Strontium nitride (strontium & nitrogen) Sr3N2
2) Potassium oxide (potassium & oxygen) K2O
5) Aluminum bromide (aluminum & bromine) AlBr3
3) Rubidium nitride (rubidium & nitrogen) Rb3N
6) Aluminum iodide (aluminum & iodine) AlI3
Types of chemical reactions
Synthesis
A+B
AB
Decomposition
AB
A+B
Single Replacement
AB + C
CB + A
Double Replacement
AB + CD
CB + AD
Tell what kind of reactions are the following (synthesis, decomposition, etc):
a.
CaCl2 + Na2CO3  CaCO3 + 2NaCl Double Replacement
g.
KOH + HNO3  H2O + KNO3 Double Replacement
b.
HC2H3O2 + NaHCO3  NaC2H3O2 + H2O + CO2 Decomp.
h.
Al2(SO4)3 + Ca(OH)2  Al(OH)3 + CaSO4 Double Replace.
c.
NaCl  Na + Cl2 Decomposition
i.
Na2O + CO2  Na2CO3 Synthesis
d.
NaOH + HCl  H2O + NaCl Double Replacement
j.
Pb(NO3)2 + 2HCl  2PbCl2 + 2HNO3 Double Replcement
e.
K + Cl2  KCl Synthesis
k.
Ca + 2HCl  CaCl2 +H2 Single Replacement
f.
K + AgCl  Ag + KCl Single Replacement
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Components of a chemical reaction
Textbook questions:
Pg. 456 Review Questions #1-4, 6, 11, 15-17;
1. They show the ration in which reactants combine and products form in a chemical reaction.
2. There are 4 chromium atoms and 6 oxygen atoms on the right side of this chemical equation.
3. The law of conservation of mass says that mass can be neither created nor destroyed. There must be the same
number of each atom on both sides of the equation.
4. The subscript describes how the molecule is put together and cannot be changed, or it will describe a different
molecule.
6. It increases.
11. It lowers the activation energy speeding up the chemical reaction
15. Energy is required to break the bonds of the reactants. In an exothermic reaction, the energy released exceeds the
energy consumed.
16. Energy
17. Energy
Pg. 457 Think and Explain #1, 2
1. a) 4Fe + 3O2 → 2Fe2O3
b) 3H2 + N2 → 2NH3
c) Cl2 + 2KBr → Br2 + 2KCl
d) CH4 + 2O2 → CO2 + 2H2O
2. No, there is different number of some types of atoms on both sides of the arrow, which means this reaction is not
balanced. The red atoms disappear and there are too many blue atoms. Atoms are neither created nor destroyed.
A. Matter
a. Identify products in a chemical equation
b. Identify reactants in a chemical equation
c. Reactants
Products
B. Energy
Exothermic reactions
Endothermic reactions
 More energy is released than is
 Less energy is released than
needed to continue the reaction
is needed to continue the reaction
 Reactants have more
 Products have more
energy than products
energy than reactants
 Energy is released to the
 Energy is absorbed
surroundings
from the surroundings
 Would feel warm
 Would feel cold
A) What types of reactions involve breaking of chemical bonds and heat being released? exothermic
B) The exothermic reaction has energy released by the reaction.
C) The endothermic reaction has energy absorbed by the reaction.
D) This reaction is cold to the touch. endothermic
E) This reaction is warm/hot to the touch. exothermic
Law of Conservation of Mass
A. In a chemical reaction mass is neither lost nor gained.
a. Atoms are rearranged
b. Equations are balanced to show Conservation of Mass
B. For the equation below, put a circle around the subscripts and a square around the coefficients.
9
C. Write and balance the following equations.
Remember the HOFBrINCl elements!:
a. Hydrogen bromide and aluminum combine to yield aluminum bromide and hydrogen.
6HBr +2Al → 2AlBr3 +3H2
b. Lead(II) phosphate and magnesium chloride combine to yield lead(II) chloride and magnesium phosphate.
Pb3(PO4)2 + 3MgCl2 → 3PbCl2 + Mg3(PO4)2
c. Chlorine combines with water to yield hydrogen chloride and oxygen.
2Cl2 + 2H2O → 4HCl + O2
Reaction rate
A. Substances must collide to react
B. The more collisions the faster the reaction
C. Four factors that affect reaction rate
a. Surface area- amount of exposed surface
b. Temperature- affects how fast particles move
c. Catalysts- affect reactions without being part of the reaction
d. Concentration- how much of a material is in a given area
Flame tests- results
A. Oxygen- Splints re-light
B. Carbon dioxide- Splints go out
Phase Changes- On the diagram below label solid, liquid, gas, melting, evaporation, condensation, freezing. (B
and D have two answers) Write right on the diagram.
10
Determine if the following is a chemical or physical change/property:
1. Oxygen is odorless and colorless
physical
2. Copper turns green when exposed to the environment chemical
3. The piece of metal is magnetic physical
4. The density of water is 1.0 gram per cubic centimeter physical
5. Diamonds are a very hard substance physical
6. The tree is 8 meters high physical
7. Sodium reacts very easily with other elements. chemical
8. Copper conducts electricity physical
9. Nitrogen is a colorless gas physical
10. The silver spoons tarnished and turned dark chemical
11. Grass grows. chemical
Covalent bonding
A. chemical bonding between nonmetals
B. electrons are shared
1. single covalent bond- one pair of shared electrons
2. double covalent bond- two pair of shared electrons
3. triple covalent bond- three pair of shared electrons
C. attraction of nuclei to the shared electrons keeps the atoms close to each other
D. molecules are formed
Write the prefixes 1-10 for naming covalent bonding:
1=
2=
3=
4=
5=
monoditritetrapenta-
6=
7=
8=
9=
10=
hexaheptaoctanonadeca-
Draw the covalent bond between the following using Lewis Dots and Structural Formulas:
a. Hydrogen and Hydrogen
2 Hydrogen and 1 Oxygen
b. Chlorine and Chlorine
3 Hydrogen and 1 Phosphorus
11
c. Carbon and 2 Oxygen
Carbon and 4 Hydrogen
d. n and 4 Hydrogen
12