Chemistry Nuclear Reactions Flashcards
An amount of energy, called the ___, is required to break up a given nucleus into its constituent protons and neutrons
binding energy
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
original nucleus
The ___ (Z) of an element describes the number of protons, whereas the mass number (A) describes the number of protons + neutrons
atomic number
Z is used as a presubscript and A is used as a presuperscript to the chemical ___ in isotopic notation
symbol
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
radionucleotide
All ___ of atoms, with the exception of hydrogen, contain protons and neutrons
nuclei
When the ___ of an atom is unstable, it may spontaneously emit particles or electromagnetic radiation (otherwise known as radioactivity)
nucleus
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
nuclear
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
obital
Every ___ (other than Hydrogen) has a smaller mass than the combined mass of its constituent protons and neutrons
nucleus
This difference is called the ___ defect
mass
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
iron
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
nucleon
___ occurs when small nuclei combine into a larger nucleus
fusion
___ 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
fission
Because the original large ___ (fission) is more unstable than its products, there is the release of a large amount of energy
nucleus
Of special interest are those ___ reactions that release more neutrons since those other neutrons will cause other atoms to undergo fission
fission
When released neutrons cause fission to occur, this in turn releases more ___, creating a chain reaction
neutrons
___ 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.
radioactive decay
Alpha decay is the ___ of an alpha particle, which is a helium nucleus that consists of two protons and two neutrons
emission
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
atomic number
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)
alpha decay
___ is the emission of a beta particle, which could be either beta negative (electron) or beta positive (positron), from the nucleus
beta decay
A positron (e+) is similar to an electron (so has minimal mass) but has a ___ charge
positive
Electrons and positrons do not normally reside in the nucleus but are emitted when a ___ or neutron in the nucleus decays
proton
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)
decay
Beta negative decay means that a ___ is consumed and a proton takes its place
neutron
In beta negative decay, the parent’s ___ is unchanged, and the parent’s atomic number is increased by one
mass number
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
decay
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
proton
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
reaction
Beta negative ___ is the only radioactive decay where the atomic number (Z’) increases in the here and now
decay
Since ___ are singly charged and about 1836 times lighter than protons, the beta radiation from radioactive decay is more penetrative than alpha radiation
beta particles
___ is the emission of gamma particles, which are high-energy photons
gamma decay
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)
nuclear decay
___ 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
gamma particles
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
electron capture
electron ___:
X, A, Z + e- -> Y, A, Z-1
capture
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
isotopes
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))
radioactive nuclei
