Test 2 Chapters 8-15

Front 1

What are atoms?

Back 1

small handful of basic building blocks that all matters are composed of. built from even more basic blocks electrons, protons, and neutrons

Front 2

What are quarks?

Back 2

perhaps strings. makes electrons, protons and neutrons.

Front 3

what are molecules?

Back 3

complicated structures combined by atoms in an infinite number of ways.

Front 4

what is inorganic molecule?

Back 4

molecule w/o both carbon and hydrogen

Front 5

what is organic molecule?

Back 5

molecule w/ both carbon and hydrogen

Front 6

how many different types of atoms are there and how many occur naturally?

Back 6

10^9 different types of atoms
92 occur naturally

Front 7

what is periodic table?

Back 7

table where elements are organized in tabular form

Front 8

what are chemists most interested about?

Back 8

electron configuration as electron exchange and sharing determine chemical composition

Front 9

what are nuclear physicists most interested about?

Back 9

properties of the nucleus

Front 10

what is written in periodic table per element?

Back 10

-atomic/proton number
-element's symbol
-mass number (grams/mole)

Front 11

what is the basic nucleonics, basic rules of the nuclear chess game?

Back 11

-atom is the basic constituent elements
-nucleus is the positively charged center of an atom and it contains all the atom's mass; composed of protons (p) and neutrons (n)
-electrons are in electron orbits/shells around nucleus and it contains no mass; orbits ~ 10^-10m; thus entire volume of an atom is described by its electronic shell. electrons are involved in chemical reactions, bonds, low energy transitions
-nucleus contains virtually all the mass of the atom and virtually none of the volume; electron shell accounts for virtually all volume and virtually none of the mass

Front 12

What is nuclear physics?

Back 12

science of the nuclear particles inside a nucleus.

Front 13

What is z, n and A?

Back 13

z = proton number
n = neutron number
A = mass number = z+n

Front 14

What states the equivalence of mass and energy?

Back 14

relation E = mc^2

Front 15

Explain the chart of nuclides.

Back 15

-where physicists map the inventory of known nuclei
-x axis = # of neutrons a nucleus contains
-y axis = # of protons it possesses
-region of stable nuclei roughly found on diagonal line where neutron number approximately equals proton #
-below diagonal line is jagged line = "neutron dripline"
-above diagonal like is jagged line = "proton dripline"
-high unstable = nuclei found above proton dripline and below neutron drip line; undergo radioactive decay readily; certain "magic numbers" for neutrons (vertical lines) and protons (horizontal lines) help make a nucleus stable

Front 16

What is an unstable nuclide?

Back 16

one that will fall apart due to it's own inherent lack of stability without any help from the outside

Front 17

what is a stable nuclide?

Back 17

a nucleus that will exist forever unless placed inside a fusion reactor or hit with a neutron or proton

Front 18

What does the left section of chart of nuclides have in each square?

Back 18

-stable nuclide
-isotopic abundance
-mass in amu

Front 19

What does the right section of chart of nuclides have in each square?

Back 19

-radioactive nuclide
-half life
-products of decay

Front 20

what are the 3 common forms of decay?

Back 20

1.beta decay
2.electron capture
3.alpha decay

Front 21

what does radioactive decay represent?

Back 21

a transition from one square in the nuclide chart to another

Front 22

what does each type of decay have in common?

Back 22

move vector

Front 23

Describe beta decay.

Back 23

-beta particle is identical to an electron except that has been emitted from a nucleus
-it carried a proton number z of -1, a neutron number of 0, a mass number of 0, and a charge of -1.
-nuclides which spontaneously fall apart by beta decay convert a neutron to a proton and emit an electron
-proton number goes up by 1, neutron number goes down by 1, and mass number remains the same
-it is isobaric
-"move" vector on nuclide chart for a nuclide undergoing beta decay is diagonal from a square toward the upper left along an isobar to a nuclide with z+1, n-1 and A is constant

Front 24

Describe alpha decay.

Back 24

-alpha particle is a helium nucleus with 2 protons z = 2, 2 neutrons n = 2.
-A=4 and nucleus is referred to as Helium-4
-typical of unstable nuclides heavier than (209)Bi, nucleus emits an alpha particle to form a new nucleus that has two fewer protons and two fewer neutrons
-"move" vector on the nuclide chart is diagonal from upper right to lower left, z-2, n-2, and A-4

Front 25

Describe electron capture.

Back 25

-a nucleus captures one of its own electrons, and internally converts a proton to a neutron
-exactly the reverse of beta decay
-isobaric
-decay "move" vector on chart is from upper left to lower right diagonally along an isobar to z-1, n+1, and A=constant

Front 26

what is similar to electron capture?

Back 26

positron emission or positron decay
instead of capturing an electron, this nucleus emits an anti-electron (positron); anti-electrons are antimatter and are immediately annihilated by contact with matter

Front 27

what determines whether a specific z and n combination is stable?

Back 27

solid squares; nuclei in empty positions can exist but are unstable and will decay spontaneously

Front 28

what is the force that controls the motions of the atomic electrons?

Back 28

electromagnetic force

Front 29

what is needed to bind the nucleus together?

Back 29

-strong attractive nuclear force of a totally different kind
-strong enough to overcome the repulsive force of the positively charged nuclear protons and to bind both protons and neutrons into the tiny nuclear volume
-nuclear force must be of short range because its influence does not extend very far beyond the nuclear "surface"

Front 30

what is nuclear force due to?

Back 30

strong force that binds quarks together to form neutrons and protons

Front 31

What does the strong nuclear force imply for the stability of a nucleus?

Back 31

-atoms with very low atomic numbers have about same number of neutrons and protons
-as z gets larger, however, stable nuclei will have more neutrons than protons
-eventually a point is reached beyond which there are no stable nuclei; nuclei with more than 83 protons are all unstable, and will eventually break up into smaller pieces (radioactivity)

Front 32

what is the largest stable nucleus?

Back 32

bismuth nucleus with 83 protons and 126 neutrons

Front 33

what does strong nuclear force prefer?

Back 33

equal numbers of protons and neutrons

Front 34

describe the difference between light nuclei and heavier nuclei

Back 34

-light nuclei (helium, carbon, nitrogen, oxygen) usually maintain 50:50 ratio, although nuclear variants/isotopes with small deviations from equality may exist and may be stable
-in heavier nuclei, bc of electric repulsion between protons, this equality no longer holds and the number of neutrons exceeds the protons
-as nuclei get heavier, the fraction of protons drops still further--about 45% in mid-range nuclei and less than 40% in the heaviest ones, those of uranium

Front 35

what would be the most stable combination for a nucleus with 56 nucleons?

Back 35

30 neutrons and 26 protons

Front 36

what is mass defect?

Back 36

-missing mass (difference between actual mass of a nucleon and its constituents)
-essentially the equivalent mass of the binding energy

Front 37

Describe the binding energy chart.

Back 37

the greater the binding energy the less the mass per nucleon

Front 38

State the characteristics of elemental abundance.

Back 38

-note log scale
-H & He are 1000-fold more abundant than all others
-relative abundances decrease rapidly with increasing z
-there are two big anomalies/departures from the smooth downward (peak near (56)Fe, minimum at (7)Li, (9)Be and (11)Bo)
-a clear "saw-tooth" pattern, especially prevalent between (12)C and (56)Fe
-Even-z elements are more abundant than their adjacent odd-z elements (even/odd proton effect)

Front 39

when did universe began?

Back 39

-when space and time came into existence, all matter in cosmos started to expand
-10^-45 sec after Big Bang when 4 fundamental forces (gravity, electromagnetism, and the strong and weak nuclear forces) were unified

Front 40

what happened during the first second or so of the universe?

Back 40

-protons, neutrons and electrons (building blocks of atoms) formed when photons collided and converted their energy into mass and 4 forces split into their separate identities
-temperature of universe also cooled during the time, from about 10^32 degrees to 10 bil degrees

Front 41

what happened 3 min after Big Bang?

Back 41

-temp cooled to 1 bil degrees
-protons and neutrons combined to form the nuclei of a few of the lighter elements, most notably Helium

Front 42

What were the elements formed immediately after Big Bang?

Back 42

-protons, neutrons, electrons
-1/1H formed from combination of proton and electron
-He formed from sequence of collisions
(proton + neutron = 2H (Deuterium-stable isotope of hydrogen)
2H + proton = 3He(stable isotope of helium)
3He + neutron = 4He(stable isotope of helium))
-sequence stopped there bc there is no stable nuclide with A=5!
(4He + neutron = 5He (unstable; decays in 10^-21 sec)
4He + proton = 5Li (unstable; decays in 10^-21 sec)

Front 43

what does the theory predict happened after 3 min about He and H?

Back 43

-universe consisted of 60 4He nuclei for every 1000 1H nuclei (H/He atom ratio = 1000/60 or about 24% 4He by weight to 76% 1H by weight (He is 4 times heavier than H))

Front 44

what happened 300,000 years after Big Bang?

Back 44

-universe had cooled to a not-quite comfortable 3000 degrees
-electrons could combine with atomic nuclei to form neutral atoms
-with no free electrons left to scatter photons of light, the universe became transparent to radiation (cosmic background radiation)

Front 45

what happened after 300 mil years after Big Bang?

Back 45

universe has simply continued to grow larger and cooler, finally creating conditions conducive to life

Front 46

what are the basic properties of stars?

Back 46

-luminosity
-temperature
-mass

Front 47

what are the needed observation of stars?

Back 47

-apparent brightness & parallax
-continuum color or spectral lines
-binary period, velocity, separation

Front 48

what does the luminosity of star depend on?

Back 48

-its temperature to the 4th power
-radius squared

Front 49

how do astronomers determine a star's luminosity?

Back 49

-star's observed brightness/flux of photons observed at the Earth in units of watts/area
-star's distance

Front 50

if we measure brightness with distance, what can we calculate?

Back 50

luminosity. if we know luminosity, we can calculate temperature

Front 51

what is stellar temperature?

Back 51

-inferred from the spectrum observed from the star
-depending upon the temperature, different atomic absorption lines are observed

Front 52

how are stars classified?

Back 52

spectra (absorption-emission lines of the elements in the stars)
temperature

Front 53

how many main types of stars are there?

Back 53

O, B, A, F, G, K AND M

Front 54

which stars are uncommon but very bright?

Back 54

O and B

Front 55

which stars are common but dim?

Back 55

M

Front 56

where is the energy from stars generated from?

Back 56

nuclear reactions (gives rise to the elements in our solar system as well)
specifically, generated from fusion most commonly by fusing H into He

Front 57

what does fusion covert to? what does it provide?

Back 57

mass energy and it provides the energy we receive from sun

Front 58

what is a problem with fusion?

Back 58

in order to get 1H to fuse, they must have enough energy to overcome the electrostatic repulsive force which comes from gravitational potential energy

Front 59

where do stars start their lives?

Back 59

in large clouds of stellar dust or Nebula consisting mostly of Hydrogen and a tiny bit of Helium, floating around in space.

Front 60

how do "clumps" (protosuns/protostars) form?

Back 60

when some of the nebula are massive enough to start to move in on themselves due to gravity. after a long time, a few warm "clumps" form

Front 61

what determines the end result or type of star?

Back 61

amount of mass in these "clumps"

Front 62

what are the 3 distinct types of stars that form from various sized protosuns?

Back 62

-dwarves
-normal (main sequence) inc our sun
-giants

Front 63

what is the basic process of star?

Back 63

1.contraction -> rising temp due to GPE
2.if T gets high enough, nuclear fusion reactions occur that stabilize the star
3.fusion continues until fue is used up
4.star begins to collapse again
5.depending upon mass:
a.star will fizzle out
b.temp will rise enough from GPE to initiate new fusion reactions using another element as fuel
(1.super nova if mass is sufficient.
2.black hole if mass is sufficient.)

Front 64

what do dwarf star start life with?

Back 64

low mass of Hydrogen
large diameter

Front 65

explain the process of "proto-dwarf"

Back 65

-spend up to 200 bil years to reach dwarf stage, slowly contracting to "star-status"
-as it contracts under it's own gravity, it's core temperature reaches around 700,000K, allowing the initiation of the first stage of Hydrogen fusion
-Hydrogen in the core is fused into heavier isotopes of Hydrogen
-proto-dwarf continues to compress it's core until the overall diameter of the proto-dwarf is about .25 of Sun's diameter
-core temp has now reached around 5-10 mil K
-when core is almost out of all of its normal Hydrogen, it compresses again, temp rise and another stage of fusion begins: fusing Hydrogen isotopes into Helium
-new star now officially RED DWARF

Front 66

how long can new dwarf spend in the next stage?

Back 66

30 bil years

Front 67

explain the process of new, red dwarf

Back 67

-as H is used up inside the core, dwarf starts to shrink, unable to produce enough heat by fusion to hold it's present size against gravity
-even though dwarf is being compressed, heat produced by gravity squeezing isn't enough to start fusing Helium into any other elements, therefore ending dwarf's long, very extended life
-red dwarf shrinks to about 1/10th of the diameter of the Sun and is a BROWN DWARF. it's core filled with Helium

Front 68

explain the dwarf

Back 68

small, but steady player
longest lasting star, bc it's gravity is at right point to keep reactions going, so it doesn't accelerate through it's reactions and die after a very short life

Front 69

explain process of normal star

Back 69

-starts out life with "normal" mass of Hydrogen and large diameter
-as it contracts under its own gravity, temp become sufficient enough to start Hydrogen fusion in the core
-star then enters main-sequence
-now about the same diameter of the Sun and same mass
-core has now reached the critical temp of 7,000,000K for the next step of fusion.
-next step of fusion is same second step as that of Dwarf stars
-Hydrogen isotopes (Deuterium) are fused into Helium
-these reactors continue for ~10 bil years until all Hydrogen in core is used to form Helium

Front 70

when and how does star become a red giant?

Back 70

when it leaves the main-sequence
when hydrogen fuel is used up and only helium remains. The helium core begins to contract, temp inc and helium begins to fuse to form carbon which causes the star to expand considerably

Front 71

what are the 6 stages in the lift of a star like our sun?

Back 71

1.protostar
2.main sequence
3.red giant/super red giant
4.planetary nebula
5.white dwarf

Front 72

what happens when a star about the mass of our Sun runs out of nuclear fuel?

Back 72

center condenses into a white dwarf while the outer atmosphere layers are expelled into space and appear as a planetary nebulae

Front 73

what is planetary nebula?

Back 73

gas that surrounds the core when the helium core runs out and the outer layers drift away from the core as a gaseous shell

Front 74

what happens after planetary nebula is formed?

Back 74

remaining core (80% of original star) enters its final stages
core becomes White Dwarf as star cools and dims

Front 75

what happens when star stops shining?

Back 75

star is dead
called Black Dwarf

Front 76

how much mass do most massive stars have?

Back 76

mass 3 times that of the Sun
some 50 times that of the Sun

Front 77

Describe massive stars

Back 77

-evolve in a similar way to a normal stars until it reaches its main sequence stage as a blue-white colored star
-stars shine steadily until hydrogen has fused to form helium
-when hydrogen fuel is consumed, massive star then becomes Red Supergiant with a helium core !0^8K, Helium contained in it begins to fuse together into Carbon
-as helium fuel is used up, giant's mass will compress its core, raising the temp and leading to a sequence of new fusion reactions, eventually leading to the creation of an iron core

Front 78

what are the fusion reactions in a giant star?

Back 78

-after fusion reaction that fuses Helium and Neon to form Magnesium the reactions become more difficult to follow, and are varied
-all of the elements produced in this stage have potential to fuse into larger nuclei in unusual ways but only fusion reactions that create elements through Iron are possible

Front 79

how come only fusion reactions that create elements through iron are possible of fusion into larger nuclei in unusual ways?

Back 79

all these reactions will produce a gamma ray or high energy photon along with the fusion product

Front 80

explain giant star

Back 80

-very short life span and enormous mass
-most will last for only 30 mil years
-life stages very short in scheme of things, and all fusion reactions are accelerated

Front 81

what is the intense heat and pressure created by mass of giant at end of its life?

Back 81

-over 3 bil K, when Iron is being formed in the core

Front 82

how come iron formed is unable to undergo any more nuclear change? what does it do instead?

Back 82

its nuclear construction will not allow it.
instead iron continues to compress into a very compact core which raises core's temp to over 100 bil K

Front 83

what determines star's fate now?

Back 83

mass of iron core

Front 84

if iron core is around 1.5 solar masses, what happens?

Back 84

-compress from a ball the same diameter as Earth to a ball only 16 km/10mi in diameter
-compression cause nuclei of iron to fuse together into one large ball of neutrons and neutrinos
-core recoils from repulsion of neutrons in a Supernova
-sudden recoil sends a shockwave through the outer layers of the star. shockwave is enough to perform fusion past Iron and all elements in the universe heavier than iron are created in this way
-after this shockwave rips through the shells surrounding the core, sending them off into space in a Supernova.
-all that is left is a ball of neutrons surrounded by a lattice of iron atoms = neutron star

Front 85

if iron core is around 3 solar masses (Chandrasekhar limit), what happens?

Back 85

-same events happen inc the supernova and the formation of neutron star, but instead of neutron star happily "floating" around, it is too massive to remain stable
-gravity takes over, causing the eventual collapse of the neutron star to a single point, theoretically forming a Black Hole or Singularity.

Front 86

what is black hole or singularity?

Back 86

theoretically, these are 2 dimensional points of gravity so strong that nothing in the universe can escape them, inc light

Front 87

what is the remnant of supernova explosion?

Back 87

crab nebula

Front 88

what are responsible for the elements in our solar system?

Back 88

nuclear reactions inside red super-giants and supernova

Front 89

if elements were generated in stars then what can you say about our solar system?

Back 89

it is not 1st generation
it must have formed after other stars had time to generate the elements we find in our solar system

Front 90

how did the heavy elements made in other stars get into our solar system?

Back 90

supernovae of giant stars spewed material into cosmos

Front 91

what happens following H and He generation?

Back 91

1.universe starts to pull itself together: gravitational instability