Understanding Isotopes and Atomic Mass

What defines isotopes of the same element?

• Same number of protons, different neutrons

• Same number of protons and neutrons

• Same number of neutrons, different protons

• Different number of protons and neutrons

Which notation is NOT used to represent isotopes?

• Element name followed by mass number

• Chemical symbol followed by atomic number

• Chemical symbol followed by mass number

• Element name followed by atomic number

How many protons does sodium-18 have?

• 6

• 7

• 11

• 18

What is the relationship between protons and electrons in a neutral atom?

• Protons are always more than electrons

• Electrons are always more than protons

• They are equal in number

• They are unrelated

What is atomic mass?

• A weighted average of all isotopes

• The mass of the heaviest isotope

• The sum of protons and neutrons

• The mass of the most abundant isotope

Why is atomic mass a weighted average?

• It considers the natural abundance of isotopes

• It averages the mass of all elements

• It considers only the heaviest isotope

• It is based on the lightest isotope

What is the atomic mass of gallium?

• 71.000 AMU

• 69.723 AMU

• 70.925 AMU

• 68.926 AMU

How do you convert percent abundance to a fraction?

• Subtract 100

• Multiply by 100

• Divide by 100

• Add 100

Which isotope of gallium is more abundant?

• Gallium-70

• Gallium-69

• Gallium-71

• Gallium-72

What is the significance of the capital Sigma (Σ) in the atomic mass calculation?

• It signifies division

• It denotes summation

• It indicates multiplication

• It represents subtraction