Isotopes and Avg. Atomic Mass Notes

Multiple Choice

What differentiates the isotopes of an element?

• number of protons

• number of neutrons

• number of electrons

• atomic number

Multiple Choice

One of the isotopes of sulfur is represented as sulfur-35 or S-35. What does the number 35 signify?

• number of protons

• number of neutrons

• atomic number

• mass number

Multiple Choice

Element A has 15 protons. Determine the number of neutrons in its isotope with mass number 33.

• 15

• 18

• 33

• 48

Multiple Choice

A neutral atom of chlorine-35 can be described as the following EXCEPT

• contains 17 protons

• contains 35 electrons

• contains 18 neutrons

• has a mass of 35 amu

Multiple Choice

An element with 11 protons, 11 electrons, and 12 neutrons is identified as

• sodium - 11

• magnesium - 12

• sodium - 23

• magnesium - 34

Multiple Choice

Which is the best nuclear symbol for a potassium atom with 21 neutrons?

Multiple Choice

The correct hyphen notation for the nuclear symbol given is

• chromium - 24

• chromium - 50

• chromium - 74

• chromium - 26

Multiple Choice

Which of the following is the nuclear symbol for lithium-6

Multiple Choice

The number 84 in strontium - 84 represents

• the atomic number

• the mass number

• the average atomic mass

• the number of electrons

Multiple Choice

Using the atomic masses and relative abundance of the isotopes of nitrogen given below, determine the average atomic mass of nitrogen.

N-14: 14.003 amu; 99.63% N-15: 15.000 amu; 0.37%

• 14.003 amu

• 14.007 amu

• 14.506 amu

• 15.000 amu

Multiple Choice

Vitellium (Vi) has the following composition:

Vi–188: 187.9122 amu; 10.861%

Vi–191: 190.9047 amu; 12.428%

Vi–193: 192.8938 amu; 76.711%

Based on this data, what can you predict about the average atomic mass of vitellium?

• It will be equal to the arithmetic mean of the masses of the three isotopes.

• It will be closer to the mass of Vi–188.

• It will be closer to the mass of Vi–193.

• It will be equal to the mass of Vi–193.

Multiple Choice

The average atomic mass of oxygen is 15.9994 amu. The atomic masses of its three isotopes are as follows:

O-16: 15.995 amu; O-17: 16.999 amu; O-18: 17.999 amu

Which isotope is most likely to have the greatest abundance in nature?

• O–16

• O–17

• O-18

• all three isotopes may be equally abundant