CHEM 121 MIDTERM EXAM PRER QUESTIONS AND ANSWERS GRADED A+
What's the difference between a physical change and a chemical change? - (ANSWER)A physical change
is only changing the state of the substance, whereas a chemical change will alter the substance
completely.
Ex: physical = water to ice
chemical = iron to rust
Name the SI base units: - (ANSWER)Length = meter
Mass = kilograms
Time = seconds
Temperature = Kelvin
Name the SI prefixes: - (ANSWER)Mono - 1
Di - 2
Tri - 3
Tetra - 4
Penta - 5
Hexa - 6
Hepta - 7
Octa - 8
Nona - 9
Deca - 10
What's the difference between precision and accuracy? - (ANSWER)Precision = the closeness of a set of
values obtained
Accuracy = the closeness of a measurement to its true value
, CHEM 121 MIDTERM EXAM PRER QUESTIONS AND ANSWERS GRADED A+
Describe significant figures - (ANSWER)
What is the factor label method? - (ANSWER)
How do you use the factor label method? - (ANSWER)
(historical and modern theories of atomic structure, i.e. Plum Pudding Model) - (ANSWER)
Given a specific isotope, explain how to find the following:
- # of protons
- # of neutrons
- # of electrons
- mass number
- approximate mass of isotope - (ANSWER)
What is percent abundance? - (ANSWER)Atomic mass = (abundance of 1st isotope) (x) + (abundance of
2nd isotope) (1-x)
How do you convert between the average atomic mass of an element and the percent abundance of its
isotopes? - (ANSWER)
Name the key regions of the periodic table, and some general properties. - (ANSWER)metals, nonmetals
and metaloids
What does the atomic mass mean? - (ANSWER)The mass of one atom of that element (in atomic mass
units, "amu")
What does the atomic number mean? - (ANSWER)The number of protons in a nucleus of an atom
What's the difference between a physical change and a chemical change? - (ANSWER)A physical change
is only changing the state of the substance, whereas a chemical change will alter the substance
completely.
Ex: physical = water to ice
chemical = iron to rust
Name the SI base units: - (ANSWER)Length = meter
Mass = kilograms
Time = seconds
Temperature = Kelvin
Name the SI prefixes: - (ANSWER)Mono - 1
Di - 2
Tri - 3
Tetra - 4
Penta - 5
Hexa - 6
Hepta - 7
Octa - 8
Nona - 9
Deca - 10
What's the difference between precision and accuracy? - (ANSWER)Precision = the closeness of a set of
values obtained
Accuracy = the closeness of a measurement to its true value
, CHEM 121 MIDTERM EXAM PRER QUESTIONS AND ANSWERS GRADED A+
Describe significant figures - (ANSWER)
What is the factor label method? - (ANSWER)
How do you use the factor label method? - (ANSWER)
(historical and modern theories of atomic structure, i.e. Plum Pudding Model) - (ANSWER)
Given a specific isotope, explain how to find the following:
- # of protons
- # of neutrons
- # of electrons
- mass number
- approximate mass of isotope - (ANSWER)
What is percent abundance? - (ANSWER)Atomic mass = (abundance of 1st isotope) (x) + (abundance of
2nd isotope) (1-x)
How do you convert between the average atomic mass of an element and the percent abundance of its
isotopes? - (ANSWER)
Name the key regions of the periodic table, and some general properties. - (ANSWER)metals, nonmetals
and metaloids
What does the atomic mass mean? - (ANSWER)The mass of one atom of that element (in atomic mass
units, "amu")
What does the atomic number mean? - (ANSWER)The number of protons in a nucleus of an atom
