Atomic Mass Quiz

What is the definition of atomic mass?

• The number of protons in an atom

• The number of neutrons in an atom

• The total number of protons and neutrons in an atom

• The average mass of all the isotopes of an element

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DOK Level 1: Recall

How do you calculate the average atomic mass of an element?

• By adding the masses of all isotopes

• By taking the simple average of the masses of all isotopes

• By taking the weighted average of the masses of all isotopes

• By multiplying the masses of all isotopes

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DOK Level 1: Recall

• 35.5 amu

• 36.0 amu

• 35.0 amu

• 34.5 amu

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DOK Level 2: Skill/Concept

Why are isotopes significant in calculating the average atomic mass of an element?

• They determine the chemical properties of the element

• They have different masses which affect the average atomic mass

• They are used to identify the element

• They do not affect the average atomic mass

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DOK Level 2: Skill/Concept

• 10.2 amu

• 10.8 amu

• 11.0 amu

• 10.5 amu

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DOK Level 2: Skill/Concept

Explain the process of calculating the weighted average of isotopes to determine the average atomic mass.

• Add the masses of all isotopes and divide by the number of isotopes

• Multiply the mass of each isotope by its relative abundance, sum these values, and divide by 100

• Multiply the mass of each isotope by its relative abundance and sum these values

• Divide the mass of each isotope by its relative abundance and sum these values

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DOK Level 3: Strategic Thinking

• 24.305 amu

• 24.500 amu

• 24.000 amu

• 25.000 amu

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DOK Level 3: Strategic Thinking

If an element has two isotopes with masses 20 amu and 22 amu, and the average atomic mass is 21 amu, what can you infer about the relative abundances of the isotopes?

• Both isotopes have equal abundance

• The isotope with mass 20 amu is more abundant

• The isotope with mass 22 amu is more abundant

• The relative abundances cannot be determined from the given information

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DOK Level 3: Strategic Thinking

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.
What is the average mass of this element?

• 74.92 amu
• 24.97 amu
• 75.01 amu
• 74.51 amu

What does the 1.00794 stand for?

• Hydrogen
• atomic number
• atomic mass
• atomic explosion