Chem Unit 1 Thing Flashcards
scientists have discovered all of the matter in our universe is made up of … different types of chemical elements. about … of these occur naturally
116; 90
all the elements that make up the universe derived from the
big bang
our universe began at a single point that was thousands of times smaller than the head of a pin. it was also … and more .. than any object we know of today. this heat still remains as …
hotter; dense; cosmic background radiation
… billion years ago, in the flash of the big bang, high energy … collided with each other, forming … Typically, when this happened the oppositely charged … and … annihilated each other instantly, converting back into …
14; photons; oppositely charged particles; matter; antimatter; high energy photons
in the first seconds of the universe, for reasons scientists cannot explain, it is estimated that … particle of … for approximately every … of … were not annihilated
one; matter; one billion particles; antimatter
as the universe expanded, both the plasma and the radiation filling it grew colder. when the universe cooled and stable atoms could form, they eventually could no longer absorb the … and the universe became … instead of being an opaque … The photons that from that time have been propagating ever since, growing fainter and less energetic
thermal radiation; transparent; fog
.. minutes after the big bang, the universe began to cool down from 10^32 degrees C to 10^9 degrees C and … and … began to …
protons; neutrons; combine
about 300,000 yrs later, the universe had cooled enough for positively charged protons to attract the … and the first … formed
negatively charged electrons; atoms
during the formation of the universe only atoms of the lightest elements-…, …, … and … were formed.
As the cloud of cosmic dust and gases from the Big Bang cooled, … formed, and these then grouped together to form … and … The high … and … within stars caused protons and neutrons to fuse together. In smaller stars like our sun, the temperatures are 15.5 million degrees C at the core, hot enough to make He and H only
H; He; Li; Beryllium; stars; galaxies; stars; pressure; temperature
in the core of hotter, larger giant stars:
… fuse to make helium
… fuse to make atoms with … protons-beryllium
… and … fuse to make atoms with … protons- carbon
… and … fuse to make atoms with … protons-oxygen, etc. and in this manner elements with up to … protons formed
hydrogens; heliums; 4; helium; beryllium; 6; carbon; helium; 8; 12
atoms of elements … to … formed in … stars
aluminum; iron; Super Giant
the most massive elements from … to … were created in … called …
iron; uranium; star explosions; supernovae
in the late 1800s scientists were passing electricity through glass tubes containing a very small amount of … like oxygen. when the power was turned on, the tube emitted light and glowed. the positive electrode is called the … and the negative called the … They called the rays … because they appeared to be coming from the … end of the tube
gas; anode; cathode; cathode rays; negative
there was much speculation about what these cathode rays were. when an object was placed in the path of the rays, the rays cast … of the objects placed in their path.
… casts a shadow-so it could be light
or it could be a stream of tiny particles
shadows; light waves
scientists found that they could … this beam by subjecting it to an additional …
deflect; electrical field
the beam deflected toward the positive charge because it carried a … meaning that the rays were …
negative charge; particles
scientists found that they could also deflect this beam by subjecting it to a …
right arm rule: in the magnetic field above a … would deflect up
this also indicates that the rays were …
magnetic field; negative charge; particles
since the particles were easily deflected, they must have either a really small … or a really large …
mass; charge
J.J. Thomson and team determined that the charge to mass ratio is: … C/kg
all gases experimented on had the same charge to mass ratio
1.76 x 10^11
physicists proposed these negatively charged particles be called …. they have the same charge to mass ratio as the negative particles generated by …, …, and … materials
electrons; static electricity; heated materials; illuminated
A scientists named Millikan squirted oil drops into a box and then passed high energy … at the box hoping to knock electrons off the air molecules and onto the oil drops. By measuring the energy necessary to stop the drops from descending, he was able to determine the … The more energy needed to prevent the drop from falling, the … the charge of the drops
x-rays; charge per drop; smaller
after the discovery of the electron, scientists believed that there must also be a … in the atom. to look for these, they used an … tube. by placing holes in the cathode so particles could move through it, they found that particles were indeed moving from the … to the … since they move towards a … plate, they must be …
positively charged particle; anode ray; anode; cathode; negative; positive
the anode rays were referred to as .., which were found to be significantly heavier than electrons.
1 proton = … x mass of electron
protons; 1840
since the heaviest anode rays in oxygen were found to be 8 x heavier than those in hydrogen, it was assumed that oxygen had 8 protons compared ot hydrogen’s 1
the … an atom has is different for each element on the periodic table
number of protons
once it was determined that atoms are made up of negatively and positively charged particles, J.J Thompson and team proposed that the structure of an atom resembled … the model featured a … sphere of matter with … embedded in it. this was based around the idea that … and .. charges attract and … charges repel
plum pudding; positive; negative electrons; positive; negative; like
ernest Rutherford used .. to test the plum pudding theory
radioactivity
radioactivity is the spontaneous emission of … by an atom. Rutherford studied emissions from the unstable element uranium. larger elements like uranium contain an atomic nucleus that can be either … and does not change, or radioactive, meaning that it …, or …, into another relement after a certain amount of time. decay can be as short as a fraction of a second and as long as a few million years
radioactive decay: nucleus breaking into … and …
stable; transforms; decays; smaller nuclei; releasing energy
three types of radiation were discovered by Ernest Rutherford:
a-rays: … particles (… charged particles with a mass roughly ..x that of the proton)
b-rays- … particles (…)
y-rays- … rays (form of … with very high ..)
alpha particles; positively; 4; beta; electrons; gamma; light; energy
physicists Geiger and marsden under the direction of ernest Rutherford shot a beam of … at a thin sheet of .. and observed the scatter pattern of the particles
alpha particles; gold foil
in the plum pudding model of the atom, positive and negative charges are dispersed evenly throughout the atom. if this model were correct, the high energy alpha particles would be slightly … by … as they passed through the foil. Rutherford and team expected all alpha particles to … the atoms in the gold foil and be deflected by only a few degrees
deflected; weak electric fields; pass through
most of the particles flew right through the foil with no deflection at all, but some … meaning that the protons are … together in the center of the atom
bounced back; clustered
the only way to account for the large angles was to assume that all the positive charge was contained within a … a small very dense … must lie within a mostly empty atom. now we know that the radius of the nucleus is … that of the atom
tiny volume; nucleus; 1/10000
since electrons were so much smaller than protons, Rutherford believed the mass of an atom would be simply related to the number of … present but the atoms were much heavier than predicted
protons
Rutherford guessed it came from another particle called a .. and verified its existence
neutron
neutrons have a mass that is essentially the same as a … and … charge.
the mass of a proton or neutron is described an …
proton; no; atomic mass unit
since electrons have a much smaller mass than a proton or neutron, the mass of an atom (in u) is generally considered to be equal to the sum of the … and … in an atom
protons; neutrons
Rutherford postulated a very small, dense nucleus containing protons and neutrons with the electrons around the outside of the atom. most of the volume of the atom is
empty space
protons and neutrons together are referred to as …, the amount of which is called the .. and is designated by the letter …
nucleons; mass number; A;
neutron number is .. and atomic number is
N; Z
atoms of the same element can have different numbrs of –> …
neutrons; isotopes
not all isotopes are found in the same … in nature
abundances
the atomic mass indicates the … of all … of a given element. this is the number reported on the periodic table
average atomic mass; isotopes
for elephants a higher N-15 to N-14 in their hair occurs in … climates, a lower ratio occurs in .. climates
dry; wet
fission: … (… achieved in lab)
Fusion: … (… achieved in lab)
separating; was; combining; was not
similarities between fission and fusion:
…
changes … and ..
large amounts of …
radioactivity; Z; A; energy
protons and neutrons continued to collide and were held together by the …, creating a more massive version of hydrogen called …, …, and trace amounts of … and …
Strong Nuclear Force; Deuterium; Helium; Tritium; Lithium
When two deuterium atoms fuse together to form a helium atom, the mass of the helium atom is … than that of the two original atoms
less
the missing mass, delta m (…), is converted to … as predicted by Einstein’s famous formula, ….
This released energy is called the …
mass defect; energy; E = delta m * c^2; binding energy
The energy of nuclear fusion powers ….
It works to make increasingly heavy ….; the source of most atoms heavier than … and …, up to …
stars; atoms; hydrogen; helium; iron
Elements heavier than iron are formed when …, in massive … As we’ll see, those heavier nuclei also release …, when they divide through …..
Energy is released whenever a nucleus gets closer to being …, the most … nucleus
stars explode; supernova explosions; energy; fission Iron; stable
fusion hold great promise as being a virtually … form of … for use on Earth. However, so far, people have only been able to unleash this energy in an … form, as a “…”
unlimited; energy; explosive; Hydrogen Bomb
while nuclear fusion reactions release energy while …. more massive elements, nuclear fission releases energy by … very massive elements
the heavy nucleus splits into …
when a nucleus heavier than iron divides into parts, the mass of the resulting nuclei is … than the original. Again, … is released
generating; dividing; lighter nuclei; less; binding energy
the energy release in a fission reaction is quite large. the smaller nuclei are stable with … neutrons, so … emerge from each fission.
The neutrons can be used to … in surrounding nuclei, causing a …
… built the first self sustaining … in Chicago in 1942
fewer; multiple neutrons; induce fission; chain reaction; Enrico Fermi; nuclear reaction
fission was first used to create an uncontrolled release of energy: the …
later, the release of energy via fission was controlled so as to create a peceful use for energy in …
… or … is the “fuel” that powers these nuclear power plants
atomic bomb; nuclear power plants; uranium; plutonium
fission occurs in the …, which … in a primary loop, which … in the secondary loop.
then, you just have a regular …/… generator which generates …
reactor vessel; heats water; boils water; steam/turbine; electricity
heavy, unstable nuclei can also become stable by emitting …. the remaining nucleus is … and more … This is called … and was first observed and studied by Henri Becquerel, Marie Curie and Pierre Curie
radiation; lighter; stable; radioactivity
there are three types of radiation:
… particles: … nuclei (… neutrons and … protons)
… particles: …
….- high energy …
helium; two; two; beta; electrons; gamma rays; electromagnetic radiation
radioactivity occurs all the time and is one of the sources of … within Earth. Heavy nuclei emit … on an ongoing basis as they move towards becoming … and more …
we are all subject to …f rome arth
heat; radiation; lighter; stable nuclei; background radiation
alpha particles are stopped by …
beta particles are stopped by a …
gamma rays are the most … and are stopped by …
sheet of paper; thin sheet of aluminum; penetrating; several meters of lead
a macroscopic sample of any radioactive substance consists of a greater number of …, which do not decay … The decay is … and the decay of one nucleus has … with the decay of any other nuclei
nuclei; at one time; random; nothing to do with
the number of decays during any time period depends on the …
after each specific time period, … of the nuclei decay. This specific time period is called the isotope’s …
the isotopes of a specific element have very different half-lies; ranging from millionths of seconds to the age of the universe
number of nuclei; half; half-life
