nuclear energy
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81 Terms
What are the two forces on an atom?
Electromagnetic and Nuclear
Electromagnetic force
when protons repel each other
Nuclear force
holds the nucleus together
An unbalanced atom is a
radioactive atom
Isotope
different versions of the same element
Can elements have stable and unstable isotopes?
yes
In standard isotopic notation what is the first number
mass number
In isotopic notation what is the bottom number
atomic number
How can you find the number of neutrons in an element?
mass number - atomic number
How do you find the mass number of an element?
protons + neutrons
Fusion
two light nuclei come together to form a heavier nuclei
When do atoms become unstable?
when the two forces are not balanced
Fission
When a heavy nucleus is split apart to create energy
What is the result of fission?
fragment in the form of small atomic nuclei is released along w large amounts of energy
Fissile
heavy atoms with large atomic masses
Chain reaction in fission
one or more of the neutrons released in fission goes on to cause fission of another nucleus, which releases more neutrons
how can we stop fission?
use light water to cool the core or use heavy water to slow down nuetrons
radioactive decay
when a nucleus randomly disintegrates until it becomes stable
Enrichment
the process of increasing the percentage of elements isotope
What are two things that have to happen to form fusion?
high temp and fast moving atoms
why do stars exist?
gravity
what increases in the gravitational attraction of a gas cloud?
pressure and temperature
What are the forces in a star?
gravity(in) and nuclear (out)
Nebula
a cloud of gas and dust
Protostar
A contracting cloud of gas and dust with enough mass to form a star
What are some attributes of a nebula?
high temp, red light, no fusion
What happens at 10 million kelvin?
hydrogen transforms into helium(fusion)
main sequence star
A star that is undergoing nuclear fusion of hydrogen into helium.
Red stars
cool stars, low energy, burn for a long time
Yellow stars
medium, burn for 10 billion years
Blue stars
high energy, burn hot and fast
Red giant
when a star is running out of hydrogen and expands ( no core fusion)
How long does a red giant expand?
until it's balanced with gravity
What does a star's death depend on?
mass
The death of a star
when nuclear fuel is gone and the star collapses due to gravity
white dwarf
A small, high density star
A white dwarf is
the smallest and most massive body in the universe
Why don't we have any black dwarfs?
the universe has not been around that long
What mass stars turn into white dwarfs?
Low mass and medium mass
Neutron stars
the remains of high-mass stars after a supernova
Features of neutron stars
small diameter, large magnetic field, emits radio waves
Pulsar
If a neutron star increases rotation
Black holes
dense objects with gravity so strong that not even light can escape
How are black holes formed?
after a supernova when stars collapse into objects more dense than neutron stars
How many layers does our sun have?
three
Source of energy for our sun
Core (fusion)
Radiative zone of the sun
transfer of energy by radiation
Convective zone of the sun
Transfer from radiative zone to surface by convection currents
Spectrometry
used to measure light from the stars
Radiation
energy emitted from an unstable isotope
Alpha particle
the nucleus of a helium atom
beta particle
a high energy, high speed electron
gamma ray
shortwave electromagnetic radiation
Which radiation has the most energy?
Gamma
More harmful particle
gamma
Form of alpha decay
4/2 a
form for beta decay
0/-1 b
why is gamma harmful
it can pass through the whole body and damage vital organs
alpha decay damage
small and in a concentrated area
beta decay damage
penetrates until it hits a large mass- covers lager areas
why are beta particles formed
a neutron converts to a proton by omitting a high speed electron
half-life
length of time required for half of the radioactive atoms in a sample to decay
what happens in alpha decay
2 protons and 2 neutrons are emitted from the nucleus and it becomes a new element
What happens in beta decay
1 electron is emitted from the nucleus and it becomes a new element
What happens during gamma decay
nucleus rearranges itself, nothing is emitted
Do half lives change for isotopes
no
what do the dice in the lab represent
isotopes
what do the number of rolls in the lab represent
time
if a radioactive material has a high probability of decaying…
the half life is shorter
what is found in the earth and what does it do?
alpha and beta particles and gamma rays and the motion. is transformed into heat
non- uniform radioactive decay leads to…
hot and cold spots in the earth and then convection currents
does the earth have leftover heat
yes, from when it was formed
why do plate tectonics continue to move
leftover energy, fission from convection currents, radioactive decay in the earth
how does the sun create energy
starts w fusion, builds up temp and pressure, light elements turn into heavy elements, turned into thermal and radiant energy
What did Annie j Cannon do?
catalogued the stars
what did Cecilia Payne discover?
stars have mainly hydrogen, and the lines on the graphs tell how hot the star is
what is heat from fission used for?
heating water, making steam, producing electricity
Is the US still building nuclear plants?
no
is nuclear energy more environmentally unsafe or more hurtful to the climate?
more hurtful to the environment bc of radioactive waste
above what atomic numbers are atoms unstable?
Pb(82)
what indicates the presence of elements in a star?
absorption lines