Calculating Average Atomic Mass and Isotope Abundance

This tutorial explains how to calculate the average atomic mass using magnesium as an example. It covers the concept of isotopes, their natural abundance, and how to compute a weighted average. The video provides a detailed calculation example, demonstrating how to use percent abundance and mass of isotopes to find the average atomic mass. It concludes with tips on identifying the most abundant isotope.

What is the average atomic mass of magnesium as shown in the periodic table?

• 12.00

• 24.31

• 28.09

• 26.98

What is the atomic number of magnesium?

• 11

• 13

• 12

• 10

What is a weighted average in the context of atomic mass?

• An average of the masses of all isotopes

• An average of the masses of the most common isotopes

• An average that takes into account the natural abundance of each isotope

• An average that ignores the natural abundance of isotopes

Which isotope of magnesium is the most abundant?

• Magnesium-26

• Magnesium-25

• Magnesium-27

• Magnesium-24

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

• By adding the masses of all isotopes and dividing by the number of isotopes

• By averaging the masses of the two most common isotopes

• By multiplying the mass of each isotope by its fractional abundance and summing the results

• By taking the mass of the most abundant isotope

What is the mass number of the most common isotope of magnesium?

• 24

• 25

• 23

• 26

Why are atomic mass units not whole numbers?

• Because of rounding errors

• Because isotopes have different masses

• Because electrons are included in the mass

• Because protons and neutrons have slightly different masses

What is the actual mass of magnesium-24 in atomic mass units?

• 24.100

• 23.985

• 24.000

• 24.015

How do you find the most abundant isotope if you don't have the abundance table?

• By calculating the mass of each isotope

• By checking the periodic table

• By rounding the average atomic mass

• By looking at the atomic number

What does the average atomic mass on the periodic table represent?

• The weighted average mass of all natural isotopes

• The mass of the heaviest isotope

• The mass of the most common isotope

• The mass of the lightest isotope