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8th Grade CBA 2
8.5BCD
1. Chemical formulas can be used to determine the number of atoms of each element in the formula. Consider
the formula for potassium permanganate, KMnO​4.​ Which does the formula represent?
A. six atoms- one of potassium, one of manganese, and four of oxygen
B. three atoms- one of potassium, one of manganese, and four of oxygen
C. three atoms- one of potassium, one of manganese, and one of oxygen
D. two atoms- one of potassium and one of permanganate
2.
Aspirin is a commonly used pharmaceutical. It is powerful pain reliever and is noted
for its ability to reduce fevers. The chemical name for aspirin is acetylsalicylic acid
and has the formula C​9​H​8​O​4​. Aspirin is synthesized in the laboratory from salicylic
acid, C​7H​
​ 6O​
​ 3,​ and acetic anhydride, C​4H​
​ 6O​
​ 3.​ Besides aspirin, a second product is
formed.
Which does the formula of aspirin represent?
A. 3 atoms- seven carbon, six hydrogen, and three of oxygen
B. 13 atoms- four of carbon, six of hydrogen, and three of oxygen
C. 16 atoms- seven of carbon, six of hydrogen, and three of oxygen
D. 21 atoms- nine of carbon, eight of hydrogen, and four of oxygen
3. Consider the chemical reaction of potassium sulfate and silver nitrate in which silver sulfate and potassium
nitrate are formed. The equation to represent this reaction is:
K​2SO​
Ag​2SO​
​
4​ + 2AgNO​3 →
​
​
4​ + 2KNO​3
What is the total number of atoms of silver shown in silver sulfate? Record and bubble in your answer below.
4. Models can be used to show the structure of an atom. The protons and neutrons are clustered in the nucleus
of the atom while electrons spin around the nucleus in an electron cloud.
What element is shown in the model?
A. Aluminum- it has 13 protons.
B. Cobalt- it has 27 protons and neutrons altogether.
C. Lithium- it has 3 valence electrons.
D. Silicon- it has 14 neutrons.
5. The table shows information about a variety of elements.
Element
Number of
Protons/Electrons
Number of Valence
Electrons
Properties
Argon
18`
8
A gas at room
temperature; Undergoes
almost no chemical
reactions
Boron
5
3
Classified as a metalloid;
Forms stable covalent and
ionic compounds
Neon
10`
8
A gas at room
temperature; Does not
readily bond with other
elements
Oxygen
8
6
A gas at room
temperature; Forms stable
covalent and ionic
compounds
Sodium
11
1
A highly reactive metal;
Forms ionic compounds
Why are argon and neon unlikely to form bonds with other elements?
A. They are gases at room temperature so they do not form bonds easily
B. They have an even number of protons and electrons.
C. With eight electrons, they are chemically stable.
D. With more than nine protons, they are too large to form bonds with other elements.
6. What is a group of elements in the periodic table?
A. a row of elements that have the same atomic number
B. a row of elements that have the same number of valence electrons
C. a column of elements that have similar chemical and physical properties
D. a column of elements that were discovered by the same scientists.
7.
A.
B.
C.
D.
Where are the valence electrons of an element found?
with the nucleus of its atoms.
in its atom’s innermost shell with the lowest energy level
outside of its atoms
in its atom’s outermost shell with the highest energy level
8. Some elements from the periodic table are listed in the table below.
Element
Protons
Neutrons
Electrons
(total)
Valence Electrons
Neon
10
10
10
8
Carbon
6
6
6
4
Hydrogen
1
0
1
1
Nitrogen
7
7
7
5
What is the order, from least to greatest, of the atomic numbers of these elements?
A. hydrogen, carbon, neon, nitrogen
B. neon, nitrogen, carbon, hydrogen
C. hydrogen, carbon, nitrogen, neon
D. carbon, hydrogen, neon, nitrogen
9. Elements are arranged in a certain order in the periodic table, from left to right and top to bottom. A pattern
of repeating physical and chemical properties of the elements emerges. What is this order of arrangement?
A. alphabetical order of the masses of the elements
B. increasing order of the atomic number of the elements
C. decreasing order of the number of valence electrons in the atoms
D. increasing order of the number of neutrons in the atoms
10. What is a group of elements in the periodic table?
A. a row of elements that have the same atomic number
B. a row of elements that have the same number of valence electrons
C. a column of elements that have similar chemical and physical properties
D. a column of elements that were discovered by the same scientists