Physical Science Web Assign Final
What makes an element distinct?
# of protons
A gram of radio active material has a half-life of one year. after 4 years, how much radioactive material will be left?
1/16 g
the half-life of carbon-14 is 5730 years. If a 1-g smaple of old carbon is 1/8 as radioactive as 1 g of a current sample, then the age of teh old sample is about
17,200 yrs
A hypothetical atom has four distinct energy states. Assuming all transitions are possible, how many spectral lines can this atom produce?
6
a certain radioactive isotope placed near a Geiger counter registers 120 counts per minute. if the half-life of the isotope is 1 day, what will the count rate be at the end of 4 days?
7.5 c/m
when radium (A-88) emit an alpha particle, the resulting nucleus has atomic number
86
When U-238 emits an alpha particle, the nucleus left behind has
90 protons
when U-239 emits a beta particle the nucleus left behind has
93 protons
Which of these statements is ture?
Molecules are the smallest subdivision of matter that still retain chemcial properties of a substance
Which of the following are electrically neutral
Neutron
An electron drops from the fourth energy level in an atom to the third level and then to the first level. two frequencies of light are emitted. how does their combined energy compare with the energy of the single frequency that would have been emitted if the electron had dropped from the fourth level directly to the first level?
The combined energies would equal the energy of the single transition
Which of these atoms has the greatest amount of electrical charge in its nucleus
Uranium
An element will decay to an element with higher atomic number the periodic table if it emits
a beta particle
what is the difference between an element and a chemical cmpound
an element consists of only one type of atom
An atom with an imbalance of electrons to protons is
an ion
The reason plutonium is not found in any appreciable amounts in natural ore deposits is because it is
artificially created
When uranium 238 absorbs a netron it
becomes a beta emitter
If a pair of helium nuclei are fused together, the result is
beryllium
Green ligh emitted by excited mercury vapor coresponds to a particular energy transition in the mercuy atom. A more energetic might emit
blue light
Which of teh following isotopes is radioactive?
carbon-14 (because it can decay)
What is it that electrons have that protons always have in equal magnitude
charge
when a beta particle is ejected from a nucleus, the nucleus has a greater
charge
When an alpha particle is ejected form a nucleus, the nuleus then has less
charge and mass
carbon-14 is produced in the atmosphere principally by
cosmic ray bombardemnt
Which of these forces determines the chemical properties of an atom
electrical force
The chemical properties of matter comes mostly from its electrons
electrons
Some alpha particles fired through a gold foil bounce backward b
electrstatic repulsion with close to gold nuclei
when the hydrogen isotope tritium-3 emits a beta particle it becomes an isotope of
helium
When two light atoms fuse together, mass
in converted to kinetic energy of neutrons
An excited hydrogen atom is capable of emitting radiation of
many more than 3 frequencies
If two protons are added to an oxygen nucleus, the result is..
neon
Tthere is a greater proportion of carbon-14 in
new bones
Does an orbital shell have to contain electrons in roder to exist?
no
when two different elemtns combine to form a compound, the resulting properties of teh compound are
no necessarily anything like those of the elemtns
Solid matter is mostly empty space, the reason solids don't fall through one another is because
of electrical forces
during a chemical reaction
old atoms stick around merely switching partners
carbon dating requires that the object being tested ontains
organic material
when neptunium emits a beta particle the result is
plutonium
Electric fources within an atomic nucleus tend to
push it apart
The quantum-mechanical probability cloud for the electron in the hydrogen atom has an average radius
quite different than the radius predicted by Bohr
An element emits 1 alph particle, 1 positron, and 3 beta particles. its atomic number
stays the same
The main reason electrons occupy discrete orbits in an atom is because
the cirumference of each orbit is an integral multiple of electron wavelengths
The half-life of a radioactive substance is independent of
the temperature of the substance, the number of atoms, wheither the substance exists in an elementary state or in a compound, and the age of the substance
Orbital electrons do not spiral into the nucleus because o
the wave nature of the electron
in a breeder reactor
uranium is converted into plutonium