Ch.2 - Atoms & ElementsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: Gallium consists of 2 isotopes. One of those isotopes is Ga-71 with a mass of 70.92 amu with an abundance of 39.892%. What is the mass number of the other isotope?

Problem

Gallium consists of 2 isotopes. One of those isotopes is Ga-71 with a mass of 70.92 amu with an abundance of 39.892%. What is the mass number of the other isotope?

Solution

We’re being asked to calculate the mass number of the other isotope of Gallium-70 (Ga-70)

We can use the following equation:


Atomic Mass=[mass×f.a.]isotope 1+[mass×f.a.]isotope 2

where:

atomic mass = average atomic mass of the element 

f.a. = fractional abundance of the isotope


To get f.a., we simply need to divide the given percent abundance by 100.


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