Practice Test: Atomic

Multiple Choice

Which is one reason why the atomic masses of elements are generally not whole numbers?

• The atomic mass of an element is the weighted average of the masses of its isotopes.

• The mass of an electron is essentially zero in comparison to the mass of a proton or neutron.

• Atomic mass is based on the weight of one carbon atom and all other elements are fractions of that.

• The abundances of the elements are fractions.

Multiple Choice

Which of the following atomic symbols is incorrect?

• K

• Cl

• N

• P

Multiple Choice

In Bohr's atomic theory, when an electron moves from one energy level to another energy level more distant from the nucleus:

• energy is absorbed

• energy is emitted

• no change occurs when this happens

• none of these occur

Multiple Choice

Alpha particles beamed at thin metal foil may

•  

  be reflected by direct contact with nuclei

• All of the above

• pass directly through without changing direction

•  

  be slightly diverted by attraction to electrons

Multiple Choice

What distinguishes the atoms of one element from the atoms of another?

• The total number of protons, neutrons, and electrons

• The number of neutrons in the nucleus

• The total number of protons and neutrons in the nucleus

• The number of protons in the nucleus

Multiple Choice

What did Thomson contribute to atomic theory?

• The discovery of negatively charged particles, now called electrons

• The discovery that negative charge is concentrated in a core, or nucleus

• The idea that electrons have quantized amounts of energy

• The discovery that positive charge is concentrated in a core, or nucleus

Multiple Choice

...

•  

  22 protons, 20 neutrons, and 20 electrons

•  

  20 protons, 20 neutrons, and 22 electrons

•  

  20 protons, 20 neutrons, and 18 electrons

Multiple Choice

How do you calculate the number of neutrons in an atom?

• Subtract one from the mass number.

• Add the atomic number and the mass number.

• Add one to the mass number.

• Subtract the atomic number from the mass number.

Multiple Choice

If the Thomson model of the atom had been correct, Rutherford would have observed:

•  

  Alpha particles going through the foil with little or no deflection.

•  

  Alpha particles greatly deflected by the metal foil.

•  

  Alpha particles bouncing off the foil.

•  

  None of the above observations is consistent with the Thomson model of the atom.

Multiple Choice

According to Dalton's postulates, how do atoms relate to elements?

• Each element is composed of many types of atoms, and the same atom may be part of two or more elements.

• Each element is composed of atoms, and the atoms of one element differ from the atoms of other elements.

• All elements are composed of atoms, and all atoms are identical.

•  

  None of the above

Multiple Choice

Ernest Rutherford proposed that the positive charge of an atom was concentrated in a dense central core, or nucleus. What evidence did he use to support this idea?

• His observation that beta particles acted the same as electrons

• His measurements of the atomic mass of gold, silver, and other elements

• His observation that gold atoms could greatly deflect the path of alpha particles

• His observation that gold atoms only slightly deflected the path of alpha particles

Multiple Choice

By knowing the number of protons a neutral atom has, you should be able to determine

•  

  the name of the atom

•  

  the number of electrons in the neutral atom

• Two of the above

Multiple Choice

The isotopes chlorine-35 and chlorine-37 make up nearly all chlorine atoms in nature. Chlorine-35 is about 3 times as abundant as chlorine-37. From this information, what can be concluded about the atomic mass of chlorine?

• It is between the masses of the two types of atoms, but closer to the mass of a chlorine-35 atom.

•  

  It is between the masses of the two types of atoms, but closer to the mass of a chlorine-37 atom.

• It is equal to the mass of a chlorine-35 atom.

•  

  It is equal to three times the mass of a chlorine-35 atom.

Multiple Choice

The first scientist to show that atoms emit any negative particles was

•  

  Ernest Rutherford

•  

  John Dalton

•  

  J. J. Thomson

•  

  Lord Kelvin

Multiple Choice

Many classic experiments have given us indirect evidence of the nature of the atom. Which of the experiments listed below did not give the results described?

•  

  The Rutherford experiment was useful in determining the nuclear charge on the atom.

•  

  The electric discharge tube proved that electrons have a negative charge.

•  

  Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.

• The Rutherford experiment proved the Thomson "plum-pudding" model of the atom to be essentially correct.

Multiple Choice

Essentially all carbon exists in nature as the isotopes carbon-12 and carbon-13. The atomic mass of carbon in amu is equal to the expression shown below. What is the value of x in the expression?

(0.9889)(12.000) + (x)(13.003)

•  

  0.4944

• 0.0111

•  

  0.1200

•  

  0.9889

Multiple Choice

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

•  

  75 protons, 130 neutrons

•  

  130 protons, 75 neutrons

•  

  75 protons, 110 neutrons

•  

  75 protons, 75 neutrons

Multiple Choice

Which among the following represent a set of isotopes? Atomic nuclei containing:

I.20 protons and 20 neutrons

II.21 protons and 19 neutrons

III.22 neutrons and 18 protons

IV.20 protons and 22 neutrons

V. 21 protons and 20 neutrons

•  

  I, IV and II, V

•  

  III, IV

•  

  I, II, III

•  

  I, V

Multiple Choice

Which one of the following statements about atomic structure is false?

•  

  Almost all of the mass of the atom is concentrated in the nucleus.

•  

  The number of protons and neutrons is always the same in the neutral atom.

•  

  The protons and neutrons in the nucleus are very tightly packed.

•  

  All of the above statements (A-C) are true.

Multiple Choice

Almost all nitrogen exists as one of two isotopes: nitrogen-14 and nitrogen-15. What information about the two isotopes is necessary to calculate the atomic mass of nitrogen?

• The number of protons in a nitrogen atom

• The mass, in amu, of an atom of each isotope

• The natural percent abundance of each isotope

• Both B and C

Multiple Choice

According to Dalton's theory, is it possible to convert atoms of one element into atoms of another? Explain.

• No. Atoms can change to other elements, but the process cannot be controlled.

• Yes. Atoms can be converted to other elements through physical changes to matter.

• Yes. Atoms can be converted to other elements through chemical changes to matter.

• No. Atoms of one element are never changed into atoms of another element through chemical changes to matter.

Multiple Choice

Which of the following statements best describes the Heisenberg uncertainty principle?

• It is impossible to accurately know both the exact location and momentum of a particle.

• The location and momentum of a macroscopic object are not known with certainty.

• The exact position of an electron is always uncertain.

• The velocity of a particle can only be estimated.

Multiple Choice

The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge is

•  

  J. J. Thomson

•  

  Lord Kelvin

•  

  Ernest Rutherford

•  

  William Thomson

Multiple Choice

• 19 p, 20 n, 18 e

• 19 p, 20 n, 19 e

• 19 p, 20 n, 20 e

Multiple Choice

Which of the following best describes an orbital?

•  

  space which may contain electrons, protons, and/or neutrons

•  

  small, walled spheres that contain electrons

•  

  a single space within an atom that contains all electrons of that atom

•  

  the space in an atom where an electron is most likely to be found

Multiple Choice

The number of electrons in an atom is the same for all neutral atoms of that element.

• True

• False

Multiple Choice

The number of neutrons in an atom is the same for all neutral atoms of that element.

• True

• False

Multiple Choice

How is atomic number different from mass number?

•  

  Atomic number equals the number of neutrons; mass number equals the number of protons and neutrons.

• Atomic number equals the number of protons; mass number equals the number of protons, electrons, and neutrons.

•  

  Atomic number equals the number of protons and neutrons; mass number equals the number of electrons.

• Atomic number equals the number of protons; mass number equals the number of protons and neutrons.

Multiple Choice

An ion is formed...

•  

  By either adding or subtracting electrons from the atom

•  

  By either adding or subtracting protons from the atom.

•  

  By either adding or subtracting neutrons from the atom.

• Two of the above are correct

Multiple Choice

How is atomic mass calculated?

• Multiply the mass of each isotope by its natural abundance, and then add the products.

• Multiply the mass of the most common isotope by its natural abundance.

• Add the number of protons and neutrons in an atom of the most common isotope.

• Find the mass of an atom of each naturally occurring isotope, and then add the masses.

Multiple Choice

Rutherford's experiment was important because it showed that:

• An atom is mostly empty space.

• The mass of the atom is uniformly distributed throughout the atom.

• Radioactive elements give off alpha particles.

• A zinc sulfide screen scintillates when struck by a charged particle.

Multiple Choice

Which of the following is (are) true?

• A

• B

• C

• A and C

Multiple Choice

The nucleus of an atom is...

• the central core and is composed of protons and neutrons.

• positively charged and has more protons than neutrons.

• negatively charged and has a high density.

• negatively charged and has a low density.

Multiple Choice

How did Dalton advance the atomic philosophy proposed by Democritus?

• Dalton used very powerful microscopes to observe atoms and advance the ideas of Democritus.

• Dalton used experimental methods to show that atoms can be combined into different compounds in simple ratios.

• Dalton relied on logical arguments to prove that atoms were indivisible and indestructible particles.

• All of the above

Multiple Choice

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains