Chemistry Nuclear Reactions

Question 1

An amount of energy, called the ___, is required to break up a given nucleus into its constituent protons and neutrons

Answer 1

binding energy

Question 2

The binding energy is converted to mass via Einstein’s E = mc^2 equation, resulting in a larger mass for the constituent protons and neutrons than that of the ___; this difference is called the mass defect

Answer 2

original nucleus

Question 3

The ___ (Z) of an element describes the number of protons, whereas the mass number (A) describes the number of protons + neutrons

Answer 3

atomic number

Question 4

Z is used as a presubscript and A is used as a presuperscript to the chemical ___ in isotopic notation

Answer 4

symbol

Question 5

The number of protons determines the identity ( name) of an element, and varying numbers of neutrons determine different isotopes of that same element. The term ___ is another generic name used to refer to any radioactive isotope, especially those used in nuclear medicine

Answer 5

radionucleotide

Question 6

All ___ of atoms, with the exception of hydrogen, contain protons and neutrons

Answer 6

nuclei

Question 7

When the ___ of an atom is unstable, it may spontaneously emit particles or electromagnetic radiation (otherwise known as radioactivity)

Answer 7

nucleus

Question 8

For ___ reactions:
elements or isotopes are changed from one to another
Reactions result in the release or absorption of large amounts of energy
Reaction rates are generally not affected by catalysts, temperature, or pressure
Protons, neutrons, or electrons can be involved

Answer 8

nuclear

Question 9

For chemical reactions:
Atoms can be rearranged by the formation or breaking of chemical bonds
Reactions generally result in the release or absorption of small amounts of energy
Reaction rates are generally affected by catalysts, temperature, or pressure.
Only electrons in the affected ___ of the atom are involved in the formation and breaking of bonds

Answer 9

obital

Question 10

Every ___ (other than Hydrogen) has a smaller mass than the combined mass of its constituent protons and neutrons

Answer 10

nucleus

Question 11

This difference is called the ___ defect

Answer 11

mass

Question 12

The binding energy per nucleon peaks at iron, which implies that ___ is the most stable atom. In general, intermediate-sized nuclei are more stable than large and small nuclei

Answer 12

iron

Question 13

Since the binding energy per ___ is greatest for intermediate-sized atoms, when small atoms combine or large atoms split, a great amount of energy is released

Answer 13

nucleon

Question 14

___ occurs when small nuclei combine into a larger nucleus

Answer 14

fusion

Question 15

___ is a process in which a large, heavy (mass number > 200) atom splits to form smaller, more stable nuclei (specially noble gases) and one or more neutron

Answer 15

fission

Question 16

Because the original large ___ (fission) is more unstable than its products, there is the release of a large amount of energy

Answer 16

nucleus

Question 17

Of special interest are those ___ reactions that release more neutrons since those other neutrons will cause other atoms to undergo fission

Answer 17

fission

Question 18

When released neutrons cause fission to occur, this in turn releases more ___, creating a chain reaction

Answer 18

neutrons

Question 19

___ is a naturally occurring spontaneous decay of certain nuclei accompanied by the emission of specific particles. It could be classified as a certain type of fission.

Answer 19

radioactive decay

Question 20

Alpha decay is the ___ of an alpha particle, which is a helium nucleus that consists of two protons and two neutrons

Answer 20

emission

Question 21

The emission of an alpha particle means that the daughter’s ___ (Z’) will be two less than the parent’s atomic number, and the daughter’s mass number (A’) will be four less than the parent’s mass number

Answer 21

atomic number

Question 22

Z daughter = Z sub parent - 2
A daughter = A sub parent - 4
The general \_\_\_ reaction is then
X, A, Z -> Y, A-4, Z-4 + alpha, 4,2
Alpha decay and fission are the only radioactive processes which the mass number changes (for the here and now)

Answer 22

alpha decay

Question 23

___ is the emission of a beta particle, which could be either beta negative (electron) or beta positive (positron), from the nucleus

Answer 23

beta decay

Question 24

A positron (e+) is similar to an electron (so has minimal mass) but has a ___ charge

Answer 24

positive

Question 25

Electrons and positrons do not normally reside in the nucleus but are emitted when a ___ or neutron in the nucleus decays

Answer 25

proton

Question 26

In beta negative ___, a neutron decays into a proton and a beta negative particle (and an antineutrino), whereas, in beta positive decay, a proton decays into a neutron and a beta positive particle (and a neutrino)

Answer 26

decay

Question 27

Beta negative decay means that a ___ is consumed and a proton takes its place

Answer 27

neutron

Question 28

In beta negative decay, the parent’s ___ is unchanged, and the parent’s atomic number is increased by one

Answer 28

mass number

Question 29

In other words, in beta negative ___, the daughter’s A is the same as the parent’s, and the daughter’s Z is one more than the parent’s
Z daughter = Z parent + 1
A daughter = A parent

Answer 29

decay

Question 30

In beta positive decay, a ___ is consumed and a neutron takes its place. Therefore, beta positive decay means that the parent’s mass number is unchanged, and the parent’s atomic number is decreased by one

Answer 30

proton

Question 31

beta negative decay:
Z daughter = Z parent - 1
A daughter = A parent
The generic beta-minus decay \_\_\_ is:
X, A, Z -> Y, A, Z + 1 -> beta negative

Answer 31

reaction

Question 32

Beta negative ___ is the only radioactive decay where the atomic number (Z’) increases in the here and now

Answer 32

decay

Question 33

Since ___ are singly charged and about 1836 times lighter than protons, the beta radiation from radioactive decay is more penetrative than alpha radiation

Answer 33

beta particles

Question 34

___ is the emission of gamma particles, which are high-energy photons

Answer 34

gamma decay

Question 35

Gamma decay usually follows another type of ___ and is a way for the nucleus to shed excess energy (similar to how an electron in an excited state emits a photon to shed energy)

Answer 35

nuclear decay

Question 36

___ carry no charge and simply lower the energy of the emitting (parent) nucleus without changing the mass number of the atomic number. The daughter’s A is the same as the parent’s, and the daughter’s Z is the same as the parent’s
Z parent = Z daughter
A parent = A daughter

Answer 36

gamma particles

Question 37

Certain unstable radionucleotides are capable of capturing an inner electron that combines with a proton to form a neutron. The atomic number is now one less than the original, but the mass number remains the same. ___ is a rare process best thought of as an inverse beta decay, following the exact same process as beta-minus decay but in reverse

Answer 37

electron capture

Question 38

electron ___:

X, A, Z + e- -> Y, A, Z-1

Answer 38

capture

Question 39

In a collection of a great many identical radioactive ___, the half-life (t sub 1/2) of the sample is the time it takes for half of the sample to decay by any of the above processes. After n half-lives, (1/2)^n of the original sample remain, whereas 1-(1/2)^n will have decayed

Answer 39

isotopes

Question 40

Let N be the number of ___ that have not yet decayed in a sample. It turns out that the rate at which the nuclei decay (delta N/delta T) is proportional to the number that remain (N). This suggests the equation:
delta N/delta t = -gammaN where gamma is known as the ___. The solution of this equation tells us how the number of radioactive nuclei changes with time, whihc is known as exponential decay:
N=N sub 0 e^-(gammaT)
where N sub zero is the number of undecayed nuclei at time t = 0. (The decay constant is related to the half-life by gamma = ln(2)/t sub (1/2) =0.693/t sub (1/2))

Answer 40

radioactive nuclei