Terms in this set (72)
an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons
the interaction that binds nucleons together in the nucleus
the energy that holds the protons together int he nucleus of an atom
mass number (A)
the number of nucleons (protons and neutrons) in the nucleus
atomic number (Z)
the number of protons in the nucleus
neutron number (N)
the number of neutrons in the nucleus
An element can be identified by its ________ number.
A nucleus is very _______.
unified mass unit (u)
used to measure weight of subatomic particles such as protons neutrons and electrons; 1 u=1.66
10^-27 kg (protons/neutrons=1 u, electrons=5
Is mass conserved in all nuclear process?
the strong force overcomes the repulsive force
How do the protons stay together in the nucleus?
stabilize the nucleus
What is the importance of neutrons in the nucleus?
the repulsive force must be balanced by the strong force
What is necessary in order for a nucleus to be stable?
As the number of protons increases, the number of neutrons must _______ even ________ to add enough attractive force to maintain stability.
At what number of protons can nuclei no longer be stable?
A stable nuclei's mass is ______ than the masses of its nucleons.
energy must be added to overcome the force's attraction
What is necessary in order to break apart a nucleus?
Binding energy needed to break up a nucleus is the __________ as the binding energy released when nucleons come together to form a stable nucleus.
mass of unbound nucleus
sum of individual nucleon masses
mass of bound nucleus
atomic mass minus the mass of the electrons
the time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
when unstable nuclei break apart into other particles
the process of radiation being emitted in the form of particles, photons, or both when a nucleus decays
the nucleus before decay
the nucleus remaining after decay
alpha particles, beta particles, gamma rays
What are the three types of radiation emitted from a radioactive material?
alpha particle (α)
stopped by a piece of paper; helium nuclei are emitted, nucleus loses two protons and two neutrons; mass loss
beta particle (β)
penetrate a few millimeters of aluminum; either electron or positron emitted; atomic number is increased or decreased by one; ratio of neutrons to protons is changed
gamma ray (γ)
penetrate several centimeters of lead; high energy photons emitted; nucleons go from higher energy level to lower energy level; energy loss
particle necessary to conserve energy and momentum; zero electric charge; very small mass; interacts weakly with matter; difficult to detect
rules for nuclear decay
1) atomic numbers on both sides are equal (charge is conserved)
2) mass numbers on both sides are equal (nucleon # is conserved)
nuclear decay series
nuclear decay continues to occur until the product has a stable nucleus
decay constant (λ)
rate of radioactive decay
large decay constant
decay quickly, short half-life
small decay constant
decay slowly, long half-life
number of decays per unit time
SI unit of activity
Half-life is ________ proportional to the decay constant.
plot of the number of radioactive parent nuclei remaining in a sample as a function of time
nuclei, carbon, nitrogen
In nuclear decay, the total number of ________ remains constant, _______ atoms decrease, and ________ atoms increase.
any process that involves a change in the nucleus of an atom (fusion, fission); system designed to maintain a controlled, self-sustained chain reaction
nucleus splits into two or more nuclei; occurs naturally only for heavy atoms; energy released meaning the nucleons must be more tightly bound and have less mass; binding energy per nucleon must increase with decreasing atomic number
two or more nuclei combine; occurs naturally only for light atoms; energy released meaning that the product must have a greater binding energy; released energy is carried primarily by gamma rays, positrons, and neutrinos
A stable nucleus can be ________ to an unstable nucleus.
occurs as a result of neutrons released in fission triggering a chain reaction
reaction fuels are processed so that the reaction can sustain itself
thermonuclear fusion reaction
energy-liberating fusion reaction
________ are more frequent in a denser gas.
the coulomb repulsion force
_____ ____________ _________ _____ between two charged nuclei must be overcome before they can fuse.
ultimate structure of matter; not divisible, no size or structure
four fundamental interactions
strong, electromagnetic, weak, gravitational
short range; binds neutrons and prints into nuclei; mediated by gluons; strongest interaction
long range; responsible for the attraction of unlike charges, repulsion of like charge, and binding of atoms and molecules; mediated by photons; second strongest interaction
short range; involved in beta decay; mediated by W and Z bosons; third strongest interaction
long range; involved in holding planets, stars, and galaxies together; mediated by gravitons; weakest interaction
All particles, other than mediating field particles, can be classified as _______ and ________.
particles that participate in the weak, gravitational, and electromagnetic interactions; thought of to be elementary particles, only six (electron, muon, tau, and a neutrino associated with each); each has an antiparticle
particles that participate in all four fundamental interactions; included mesons and baryons; made of quarks
unstable hadrons; one quark and one antiquark
hadrons with masses equal to or greater than the proton mass (protons , neutrons); three quarks
type of hadron; three antiquarks
6 types of quarks
up (u), down (d), charm (c), strange (c), top (t), bottom (b)
up, charm, top
Which quarks have a positive charge (+2/3 e)?
down, strange, bottom
Which quarks have a negative charge (-1/3 e)?
associated with each quark; has a proportional but opposite charge of the quark
Which quarks are needed to make up hadrons?
charm, strange, top, bottom
Which quarks are found in high-energy situations?
strong force for quarks
total charge of a proton
total charge of quarks in a neutron
helps to explain the early universe; incomplete
exists only at high energies (electromagnetic and weak forces merge)
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