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 bring to your exam?
o Pencils
o Calculator
o 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.
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.
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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
c. How many electrons can be found in the second energy level of an atom? 8
d. 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. 816O and 817O
ii. 50122Sn and 52122Te
iii. 1739Cl and 1939K
iv. 50121Sn and 50119Sn
c. Identify the most abundant isotope for each element.
i. Fe-54 Fe-56 Fe-57 Fe-58
ii. O-16 O-17 O-18
iii. Mg-24 Mg-25 Mg-26
iv. S-32 S-33 S-34 S-36
v. Ar-36 Ar-38 Ar-40
vi. Hg-196 Hg-198 Hg-199 Hg-202 Hg-204
vii. Kr-78 Kr-80 Kr-82 Kr-83 Kr-84 Kr-86
d. 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.
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
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. Which elements are alkali metals? Group/Family 1
b. Which elements are alkaline earth metals? Group/Family 2
c. Which elements are halogens? Group/Family 17
d. Which elements are noble gases? Group/Family 18
D) Identifying elements by period (which row?)
a. Which elements have one electron shell? Period 1
b. Which elements have two electron shells? Period 2
c. Which elements have three electron shells? Period 3
d. Which elements have four electron shells? Period 4
e. Which elements have five electron shells? Period 5
f. Which elements have six electron shells? Period 6
g. Which elements have seven electron shells? Period 7
E) Identifying elements by area of the periodic table
a. Which elements are metals? Blue
b. Which elements are nonmetals? Yellow
c. Which elements are metalloids? Pink
d. Which elements are transition metals? Purple/pink in top
Periodic table
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
_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+
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 2-
d. 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:
1
a. Sodium & Phosphorus
b. Lithium & Chlorine
1
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)
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