Atomic Structure - Lesson 4 (Calculating Atomic Mass)

What is the atomic number of an element?

• The atomic number of an element is the number of molecules in its nucleus.

• The atomic number of an element is the number of neutrons in its nucleus.

• The atomic number of an element is the number of electrons in its nucleus.

• The atomic number of an element is the number of protons in its nucleus.

How is atomic mass calculated?

• By counting the number of electrons in an atom.

• By measuring the temperature of an atom.

• By dividing the mass of an atom by its volume.

• By summing up the masses of protons and neutrons in an atom.

What is an isotope?

• A variant of an element with the same number of protons but a different number of electrons.

• A variant of an element with the same number of neutrons but a different number of protons.

• A variant of an element with the same number of protons but a different number of neutrons.

• A variant of an element with the same number of electrons but a different number of protons.

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What is isotopic abundance?

• The relative amount of each different isotope of an element found in a sample.

• The total amount of isotopes in an element.

• The number of neutrons in an atom of an element.

• The average mass of all isotopes of an element.

What is the average atomic mass?

• Sum of the masses of all the isotopes

• Weighted average of the masses of all the isotopes

• The mass of the least common isotope

• The mass of the most common isotope

Which subtopic deals with calculating atomic mass?

• Thermodynamics

• Atomic Mass Calculation

• Electromagnetism

• Quantum Mechanics

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What is the unit of atomic mass?

• kg

• g

• lb

• amu

Calculate the average atomic mass of silver.

• 106.38649amu

• 111.91896amu

• 107.8677amu

• 121

Compute the average atomic mass for silicon:

• 27.977 amu

• 28.09 amu

• 28.976 amu

• The average mass cannot be determined from provided information.

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An isotope has three forms.  30% have a mass of 4 amu, 20% have a mass of 5 amu and 50% have a mass of 3 amu.  Average atomic mass will be closest to

• 2 amu
• 3 amu
• 4 amu
• 5 amu