Average Atomic Mass and Isotopes

Average Atomic Mass and Isotopes

Multiple Choice

The mass number of an element that has 18 protons, 18 electrons, and 19 neutrons is

• 12.5

• 25

• 13

• 37

Multiple Choice

The atomic number of an element that has 9 protons, 9 electrons, and 20 neutrons is

• 9

• 19

• 10

• 28

Multiple Choice

If the number of electrons changes you make a(an)

• ion

• new element

• isotope

• isomer

Multiple Choice

How many neutrons does Uranium-239 have

• 92

• 239

• 147

• 331

Multiple Choice

Which statement about subatomic particles is true

• Protons, neutrons, and electrons all have about the same mass

• neutrons have no charge and no mass

• unlike protons or neutrons, electrons have no mass

• an electron has far less mass than either a proton or a neutron

Multiple Choice

Which of the following is unique for any given element

• the number of neutrons

• the number of protons

• the charge on the electron

• the mass of the neutron

Multiple Choice

Which is true about Oxygen-17, and Oxygen-18

• They do not have the same number of protons

• They are isotopes of oxygen

• Their atoms have an identical mass

• They have the same mass number

Multiple Choice

How many protons are present in phosphorus-31

• 15

• 31

• 16

• 46

Multiple Choice

Two isotopes of carbon are carbon-12 and carbon 14. These isotopes differ from each other by two protons

• true

• false

Multiple Choice

What is the charge of an atom that has lost one electron

• 1-

• 1+

• 2-

• 2+

Multiple Choice

What is the charge of an atom that has gained one electron

• 1-

• 1+

• 2-

• 2+

Multiple Choice

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.

What is the average mass of this element?

• 74.92 amu

• 75.01 amu

• 24.97 amu

• 74.51