Estimating Average Atomic Mass

Isotopes are atoms of the same element with different #’s of __________ & therefore different __________.

• neutrons ; atomic numbers

• protons ; atomic numbers

• electrons ; mass numbers

• neutrons ; mass number

The average atomic mass can be estimated by using the percent abundances of each isotope. Typically, the average atomic mass is closest to...

• the mass of the isotope with the lowest abundance.

• the mass of the isotope with the greatest abundance.

• the sum of the masses of all isotopes

The average atomic mass for an element is...

• the protons and neutrons in one isotope

• the number of protons in the element

• a weighted average of the masses of all isotopes of the element.

• the protons - the electrons

What is the mass number defined as?

• the number of protons
• the number of protons and neutrons
• the number of neutrons
• the number of protons and electrons

which atom has  4 neutrons?

• Li-6
• Li-7
• Li-8
• they have the same # of neutrons

Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208.  The average atomic mass of lead is 207.2.  Which isotope of lead is likely to be the most abundant.

• 204
• 206
• 207
• 208

Based on the data, the average atomic mass will be closer to...

• 10

• 11

• half way between 10 and 11

• 5

Based on the data, the average atomic mass will be between...

• 28 and 29

• 29 and 30

• 30 and 31

• 14 and 15

Based on the data, the average atomic mass will closest to...

• 36

• 40

• 18

• 57

Based on the data, the average atomic mass will be....

• closer to 35

• closer to 37

• half way between 35 and 37