Physical Science Web Assign Final

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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


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