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ATOMIC STRUCTURE



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

1. 

Dalton's atomic theory helped to explain the law of conservation of mass because it stated that atoms
a.
could not combine.
c.
all had the same mass.
b.
could not be created or destroyed.
d.
were invisible.
 

2. 

Dalton's theory essentially agreed with the present atomic theory EXCEPT for the statement that
a.
all matter is made up of small particles called atoms.
b.
atoms are not divided in chemical reactions.
c.
atoms of the same element are chemically alike.
d.
all atoms of the same element have the same mass.
 

3. 

When an electrical current passed through a glass tube, a paddle wheel placed between the electrodes moved. Scientists concluded that
a.
a magnetic field was produced.
b.
particles were passing from the cathode to the anode.
c.
there was gas in the tube.
d.
atoms were indivisible.
 

4. 

Rutherford fired positively charged particles at metal foil and concluded that most of the mass of an atom was
a.
in the electrons.
c.
evenly spread throughout the atom.
b.
concentrated in the nucleus.
d.
in rings around the atom.
 

5. 

The nucleus of an atom has all of the following characteristics EXCEPT that it
a.
is positively charged.
c.
contains nearly all of the atom's mass.
b.
is very dense.
d.
contains nearly all of the atom's volume.
 

6. 

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the
a.
electron.
c.
neutron.
b.
proton.
d.
atom.
 

7. 

Atoms of the same element that have different masses are called
a.
moles.
c.
nuclides.
b.
isotopes.
d.
neutrons.
 

8. 

The average atomic mass of an element depends on both the masses of its isotopes and each isotope's
a.
atomic number.
c.
relative abundance.
b.
radioactivity.
d.
mass number.
 

9. 

Zn-66 (atomic number 30) has
a.
30 neutrons.
c.
36 neutrons.
b.
33 neutrons.
d.
96 neutrons.
 

10. 

Molar mass
a.
is the mass in grams of one mole of a substance.
b.
is numerically equal to the average atomic mass of the element.
c.
both a and b
d.
neither a nor b
 

11. 

The mass of 1 mol of chromium (atomic mass 51.996 amu) is
a.
12 g.
c.
51.996 g.
b.
198 g.
d.
6.02 ´ 1023 g.
 

12. 

The mass of a sample containing 3.5 mol of silicon atoms (atomic mass 28.0855 amu) is
a.
28 g.
c.
72 g.
b.
35 g.
d.
98 g.
 

13. 

A prospector finds 39.39 g of gold (atomic mass 196.9665 amu). She has
a.
1.20 ´ 1023 atoms.
c.
4.30 ´ 1023 atoms.
b.
2.30 ´ 1023 atoms.
d.
6.02 ´ 1023 atoms.
 

14. 

The distance between two successive peaks on a wave is its
a.
frequency.
c.
quantum number.
b.
wavelength.
d.
velocity.
 

15. 

A line spectrum is produced when an electron moves from one energy level
a.
to a higher energy level.
b.
to a lower energy level.
c.
into the nucleus.
d.
to another position in the same sublevel.
 

16. 

The Bohr model of the atom was an attempt to explain hydrogen's
a.
density.
c.
mass.
b.
flammability.
d.
line-emission spectrum.
 

17. 

If electrons in an atom have the lowest possible energies, the atom is in the
a.
ground state.
c.
excited state.
b.
inert state.
d.
radiation-emitting state.
 

18. 

According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus
a.
in specific, allowed orbits.
b.
in one fixed orbit at all times.
c.
at any of an infinite number of distances, depending on its energy.
d.
counterclockwise.
 

19. 

The change of an atom from an excited state to the ground state always requires
a.
absorption of energy.
c.
release of visible light.
b.
emission of electromagnetic radiation.
d.
an increase in electron energy.
 

20. 

Which statement regarding the "gold foil" experiment is false?
a.
It was performed by Rutherford and his research group early in the 20th century.
c.
The alpha particles were repelled by electrons.
b.
Most of the alpha particles passed through the foil undeflected.
d.
It suggested the nuclear model of the atom.
 

21. 

In the Rutherford gold foil experiment, the fact that most of the alpha particles were not deflected as they passed through the gold foil indicates that
a.
the nucleus is positively charged.
c.
atoms are solid spheres touching each other in the solid state.
b.
the atom is mostly empty space.
d.
gold is very dense.
 

22. 

Which response includes all the following statements that are true, and no false statements?
I.   Isotopes of an element differ only in the number of protons.
II.  The number of protons in an atom is its atomic number.
III. The mass number of an atom is the sum of the number of protons
     plus electrons in the atom.
IV.  The volume occupied by the nucleus of an atom represents a large
     percentage of the total volume of the atom.
a.
I and III
c.
II and IV
b.
II, III, and IV
d.
II
 

23. 

The law of conservation of mass follows from the concept that
a.
atoms are indivisible.
b.
atoms of different elements have different properties.
c.
matter is composed of atoms.
d.
atoms can be destroyed in chemical reactions.
 

24. 

Which of the following is NOT part of Dalton's atomic theory?
a.
Atoms cannot be divided, created, or destroyed.
b.
The number of protons in an atom is its atomic number.
c.
In chemical reactions, atoms are combined, separated, or rearranged.
d.
All matter is composed of extremely small particles called atoms.
 

25. 

In a glass tube, electrical current passes from the negative electrode, called the ____, to the other electrode.
a.
cathode
c.
electron
b.
anode
d.
millikan
 

26. 

The discovery of the electron resulted from experiments using
a.
gold foil.
c.
neutrons.
b.
cathode rays.
d.
alpha particles.
 

27. 

The mass of a neutron is
a.
about the same as that of a proton.
c.
double that of a proton.
b.
about the same as that of an electron.
d.
double that of an electron.
 

28. 

Most of the volume of an atom is occupied by the
a.
nucleus.
c.
electron cloud.
b.
nuclides.
d.
protons.
 

29. 

Which response includes all the following statements that are true, and no false statements?
I.   Isotopes of an element differ only in the number of protons.
II.  The number of protons in an atom is its atomic number.
III. The mass number of an atom is the sum of the number of protons
     plus electrons in the atom.
IV.  The volume occupied by the nucleus of an atom represents a large
     percentage of the total volume of the atom.
a.
I and III
c.
II and IV
b.
II, III, and IV
d.
II
 

30. 

Which of the responses contains all the statements that are consistent with the Bohr theory of the atom (and no others)?
I.   An electron can remain in a particular orbit as long as it     
     continually absorbs radiation of a definite frequency.
II.  The lowest energy orbits are those closest to the nucleus.
III. An electron can jump from the n= 1 to n=3 by emitting
     radiation of a definite frequency.
a.
II and III
c.
I and II
b.
II
d.
III
 

Short Answer
 

31. 

How has Dalton's theory about atomic particles been modified by modern science?
 

32. 

Consider only the following quantum levels for the H atom.

_____________ n = 5
_____________ n = 4
_____________ n = 3
_____________ n = 2
_____________ n = 1
The emission spectrum of an excited H atom will consist of transitions between these levels.
(i) How many emission lines are possible, considering only the five quantum levels?
above? _____________________
(ii) Photons of the highest frequency will be emitted in a transition from the level with n =
____ to the level with the n = _____ .
(iii) The emission line having the longest wavelength corresponds to a transition from the
level with n = ____ to the level with n = _____ .
 

Problem
 

33. 

How many atoms are present in 8.00 mol of chlorine atoms?
 

34. 

How many moles of iron are equivalent to 1.11 ´ 1025 atoms?
 



 
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