Chem 115 - Nuclear Chemistry

Front 1

Nucleons are...

Back 1

Nuclear protons and neutrons

Front 2

What refers to the potential energy of a particular nucleus compared with the sum of the potential energies of its component protons and neutrons?

Back 2

Thermodynamic stability

Front 3

When a nucleus undergoes decomposition to form a different nucleus it is called...

Back 3

Radioactive decay

Front 4

What term describes the probability that a nucleus will undergo radioactive decay?

Back 4

Kinetic stability

Front 5

Emission of an electron in decay is called...

Back 5

Beta emission

Front 6

Which element has the largest number of stable isotopes/nuclides?

Back 6

Tin

Front 7

T/F: All nuclides with 84 or more protons are unstable with respect to radioactive decay.

Back 7

True

Front 8

T/F: Light nuclides are stable when the neutron-proton ratio is one, and heavier ones require a greater ratio.

Back 8

True

Front 9

T/F: Certain combinations of protons and neutrons confer special stability, like those with even numbers of protons and neutrons versus odd numbers.

Back 9

True

Front 10

What are the two types of radioactive decay processes?

Back 10

Those that involve a change in the mass number, and those that do not.

Front 11

What is an alpha particle?

Back 11

A helium nucleus: 4,2,He

Front 12

The splitting of a heavy nuclide into two lighter nuclides with similar mass numbers is...

Back 12

Spontaneous fission

Front 13

T/F: In all beta decay, the NET effect is to change a neutron to a proton. We therefore expect nuclides that lie above the zone of stability (those nuclides whose neutron/proton ratios are too high) to be beta particle producers.

Back 13

True

Front 14

T/F: The unstable nucleus creates an electron as it releases energy in the decay process. The electron thus results from the decay process rather than being present before the decay occurs.

Back 14

True

Front 15

A high energy photon is a...

Back 15

Gamma ray

Front 16

T/F: The emission of gamma rays is one way a nucleus with excess energy (in an excited nuclear state) can relax to its ground state.

Back 16

True

Front 17

What occurs for nuclides that are below the zone of stability (i.e., their neutron/proton ratios are too small)? What is the net effect?

Back 17

Positron emission, where the net effect is to change a proton to a neutron

Front 18

A positron is the antiparticle of the electron, and when a positron collides with an electron, the particulate matter is changed to electromagnetic radiation in the form of high energy photons (gamma rays). What is this process called?

Back 18

Annihilation

Front 19

What is the process called in which an inner-orbital electron is captured by the nucleus (thus the electron is on the left side of the decay equation, and it ALWAYS releases gamma rays as a way to release excess energy)?

Back 19

Electron capture

Front 20

T/F: Often, a radioactive nucleus cannot reach a stable state through a single decay process. In such a case, a decay series occurs until a stable nuclide is formed.

Back 20

True

Front 21

T/F: The rate of radioactive decay equals -∆N/∆t (where N is the number of nuclides in a given sample) which is directly proportional to N.

Back 21

True

Front 22

The change of one element into another is a...

Back 22

Nuclear transformation

Front 23

Devices used to give particles very high velocities are...

Back 23

Particle accelerators (they are usually accelerating positrons because a positron will repel the positively charged nucleus and the accelerator can help it overcome this)

Front 24

Elements with atomic numbers greater than 92 (which are usually synthesized) are called...

Back 24

Transuranium elements

Front 25

What is the most familiar instrument for measuring radioactivity?

Back 25

A Geiger counter

Front 26

T/F: The Geiger counter takes advantage of the fact that high-energy particles from radioactive decay processes produce ions when they travel through matter.

Back 26

True

Front 27

T/F: Carbon-14 is continuously produced in the atmosphere when high-energy neutrons from space collide with nitrogen-14, and it continuously decays through beta emission.

Back 27

True

Front 28

Radioactive nuclides that can be introduced into organisms in food or drugs and whose pathways can be traced by monitoring their radioactivity are...

Back 28

Radiotracers

Front 29

∆m in ∆E=∆mc^2 is called...

Back 29

The change in mass or mass defect

Front 30

T/F: The energy changes observed for nuclear processes are extremely large compared with those observed for chemical and physical changes.

Back 30

True

Front 31

The energy required to decompose a nucleus into its component nucleons (versus forming it, as used in the 16,8,O example) is...

Back 31

Binding energy

Front 32

Combining two light nuclei to form a heavier, more stable nucleus is called...

Back 32

Fusion

Front 33

Splitting a heavy nucleus into two nuclei with smaller mass numbers is called...

Back 33

Fission

Front 34

T/F: Both fission and fusion are exothermic.

Back 34

True

Front 35

If, on average, less than one neutron causes another fission event, the process dies out and the reaction is said to be...

Back 35

Subcritical

Front 36

If EXACTLY one neutron from each fission event causes another fission event, the process sustains itself at the same level and is said to be...

Back 36

Critical

Front 37

If MORE than one neutron from each fission event causes another fission event, the process rapidly escalates and the heat buildup causes a violent explosion, which is...

Back 37

Supercritical

Front 38

To achieve the critical state, a certain mass of fissionable material, called the _ _, is needed.

Back 38

Critical mass