12-4 Isotopes & Average Atomic Mass

Front

What is the atomic mass of an element?

Back

The weighted average of the masses of the isotopes of the element.

Front

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

Back

Multiply the mass of each isotope by its relative abundance (as a decimal), then sum these values.

Front

What is an isotope?

Back

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons.

Front

What is the mass number of an isotope?

Back

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Front

How many protons are in the isotope Fluorine-18?

Back

9 protons.

Front

What is the correct symbol for Fluorine-18?

Back

18F or F-18.

Front

What is the difference between carbon-12 and carbon-14?

Back

They differ in the number of neutrons; carbon-12 has 6 neutrons, while carbon-14 has 8 neutrons.

Front

What is relative abundance in isotopes?

Back

Relative abundance is the percentage of each isotope present in a naturally occurring sample of an element.

Front

If an element has isotopes with masses of 75.23 amu (24.1%), 74.61 amu (48.7%), and 75.20 amu (27.2%), what is the average atomic mass?

Back

74.92 amu.

Front

What is the significance of the atomic number?

Back

The atomic number indicates the number of protons in an atom and defines the element.