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CHEMISTRY TEST
NAME: ______________________
ATOMIC STRUCTURE AND
DATE: ______________________
ELECTRON CONFIGURATION
Directions: For each of the following questions, choose the number that best answers the
question and place it on your answer sheet.
Directions: For each of the following questions, all major steps must be shown to receive
full credit.
Atomic Structure and Electron Configuration
Level 1
Multiple Choice
1. How many electrons are there in the third shell of the atom with atomic number 23?
1) 3
2) 8
3) 10
4) 11
5) 13
ANS: 4
2. Which is the mass number of an ion of potassium, K+, having 18 electrons, 19 protons,
and 20 neutrons?
1) 36
2) 37
3) 38
4) 39
ANS: 4
3. The atomic number of an element is the number of l) neutrons in the nucleus;
2) electrons in the outermost shell;
3) protons the nucleus;
4) electrons in
the nucleus.
ANS: 3
4. The development of the concept that elements have isotopes helps explain why
atomic
1) nuclei are neutral;
2) nuclei are charged;
3) masses are
not whole numbers;
4) masses differ from atomic numbers.
ANS: 3
5. How many neutrons are present in an atom of silver which has a mass number of 108?
1) 14
2) 47
3) 61
4) 108
Note: 47Ag
ANS: 3
6. In an experiment by Rutherford, the deflection of alpha particles backward when shot
at gold foil indicated
1) all matter was continuous and impenetrable.
2) the alpha particle was very light and positively charged.
3) all the positive charge and most of the mass of the atom was concentrated in a
small volume.
4) all of the mass and charge of the atom were contained in the same region.
ANS: 3
7. Which particle has a mass of approximately one atomic mass unit?
1) Proton
3) Alpha particle
2) Electron
4) Carbon-l2 nucleus
5) Oxygen-16 nucleus.
ANS: 1
8. According to the quantum theory of light, the separate packets of energy by which
the light waves travel are called 1) molecules;
2) protons;
3) ions;
4) neutrons;
ANS: 5
5) photons.
9. The frequency and wavelength of a wave are
1) equal;
2) inversely proportional;
3) directly proportional;
ANS: 2
4) unrelated.
10. An ion has 13 electrons, 12 protons, and 14 neutrons. What is the mass of the ion? 14 a.m.u.
2) 25 a.m.u.
3) 26 a.m.u.
4) 27 a.m.u.
5) 39 a.m.u.
ANS: 3
1)
11. The bright-light spectra observed for different elements result from
1) collisions between electrons of different energies.
2) changes within the nucleus of the atom.
3) electrons changing directly into energy.
4) electrons moving to lower energy levels.
ANS: 4
12. When Rutherford bombarded gold foil with positively charged alpha particles,
most of the particles went through but some were deflected back. Rutherford
concluded
that atoms
1) are solid spheres.
3) contain neutral particles.
2)
have negative charges.
4) have positive nuclei
ANS: 472. Fluorine has an atomic number of 9 and an atomic mass of 19. The number of
electrons
in the second energy level in this atom is l) 7;
2) 2;
3) 9;
4) l0;
5) 12.
ANS: 1
13. A nucleus having the following description: protons = 16 and neutrons = 15
an atom of l) P;
2) H;
3) Ga;
4) O;
5) S.
ANS: 5
would be in
14. The atom whose outermost shell structure most closely resembles that of neon
(atomic number 10) has the atomic number
1) 11;
2) 2;
3) 16;
4) 18;
5) 31.
ANS: 4
15. An atom of the element beryllium consists of 4 protons, 5 neutrons, 2 K electrons, and
2 L electrons. The atomic mass of this atom is 1) 13;
2) 9;
3)5;
4) 4.
ANS: 2
16. Positive ions are formed from neutral atoms by the loss of
1) neutrons;
2) protons;
3) nuclear charge;
4) electrons;
ANS: 4
17. The atomic number of an element is based on the
1) atomic mass.
3) density of its vapor.
2) mass number.
in atom.
5) number of protons in atom.
ANS: 5.
5) energy.
4) number of neutrons
18. A lithium atom has an atomic number of 3 and a mass of 7. The number of electrons
which it has in the 1st shell is
1)1;
2) 2;
3) 3;
4) 4.
ANS: 2
19. The atoms of the isotopes of hydrogen l) have one proton but differ in the number of
electrons;
2) have one proton but differ in the number of neutrons;
3) have
the same mass;
4) differ in the number of protons.
ANS: 2
20. Which particle consists of 13 protons, 14 neutrons, and 10 electrons?
1) Neon atom
3) Aluminum ion
2)
Sodium atom
4) Silicon atom
5) Phosphide ion
ANS: 3
21. When lithium (at. no. 3) loses its single 2nd shell electron, its electronic structure
resembles that l) hydrogen, 1H;
2) helium, 2He;
3) boron, 5B;
4) neon, 10Ne.
ANS: 2.
22. The number of electrons in the highest energy level of
1) 2;
2) 4;
3) 5;
4) 6;
ANS: 1
20Ca
is
5) 8.
23. Which one of the following would contain the other four?
1) atom
2) element
3) nucleus
4) molecule
5) compound
ANS: 5
24. The atomic mass of arsenic is 74.92. What does this mean?
1) An atom of arsenic has a mass of 74.92 grams.
2) There are 74.92 atoms of arsenic in one gram.
3) An atom of arsenic is 6.234 times as heavy as a carbon-12 atom.
4) An atom of arsenic is 6.243 times as heavy as an oxygen-16 atom.
ANS: 3
25. A nucleus having the following description: protons = 16 and neutrons = 15
would be in
an atom of l) P;
2) H;
3) Ga;
4) O;
5) S.
ANS: 5
26. Oxygen (atomic number 8) has how many electrons in the second energy level?
1) 2
2) 6
3) 7
4) 8
5) none of these
ANS: 2
27. When an atom is changed to a negatively charged ion,
1) oxidation occurs.
.
2) protons are lost.
4) there is an increase in radius.
3) electrons are lost.
5) the ion becomes a better electron acceptor.
ANS: 4
28. How many electrons are in a chromium(III) ion, 2452Cr+3 ?
1) 52
2) 49
3) 27
4) 24
5) 21
ANS: 5
29. The observed behavior of electrically charged bodies toward one another helps in
explaining all of the following except:
1) Adding electrons to one end of a metal wire causes electrons to escape from the other
end.
2) Electrons are attracted by the nucleus of an atom.
3) The electron in a hydrogen atom does not collapse into the nucleus, which is a proton.
4) Connecting electrodes to a power source causes migration of ions in solutions.
5) It takes energy to remove an electron from an atom.
ANS: 3
30. An atom has atomic number 13 and mass number 27. The number of valence electrons
is 1) 5;
2) 2;
3) 3;
4) 4;
5) none of these.
ANS: 3
31. In which set do all symbols have the same number of electrons?
1) He0, Ne0, Ar0
3) S-2, Cl-, Ar0
2) Li+, Ne0, Na+
0
+
0
+
Ar , Na
5) Ar , K , Mg+2
ANS: 3
39. The formula for one molecule of hydrogen is
1) H2;
2) 2 H;
3) 2 H+;
4) 2 H-;
5) none of these.
ANS: 1
4) Cl-,
32. Avogadro’s number, 6.02 x 1023, indicates
1) the amount of charge on an electron.
2) the number of particles in a mole of particles.
3) a comparison of the mass of the proton and the electron.
.
4) the weight of 1 atomic mass unit.
ANS: 2
33. How many moles are there in 100 grams of the element helium?
1) 12.5 m.
2)
25.0 m.
3) 50.0 m.
4) 100 m.
5) 400 m.
ANS: 2
34. How many grams are there in 1.5 moles of zinc?
1) 15 grams
2) 47 grams
3) 65 grams
4) 98 grams
ANS: 4
35. Given a candle that is originally 8.50 cm high and it burns to a height of 2.50 cm in 5.50
minutes. What is the rate that the candle burns?
1) 2) 3) 4)
ANS: 4
36. If the rate of candle burning is 2.50 cm/min, how tall is the candle after burning 2.60
minutes if it was originally 10.00 cm tall?
1) 2) 3) 4)
ANS: 4
37. How long does it take for the candle to burn to 0.500 cm at a rate of 3.500 cm/min if the
candle was originally 20.00 cm tall?
1) 2) 3) 4)
ANS: 4
38. Which of the following scientists was credited with the discovery of the electron as
a result of work with cathode rays?
a. Dalton
b. Thomson c. Millikan
d. Newton
39. Which of the following statements was not part of Dalton’s hypothesis on the
structure of matter?
a.
All matter is made of atoms.
b.
Atoms of the same element are identical.
c.
Atoms are made of protons and electrons.
d.
Atoms unite in definite ratios to form compounds.
40. The electric charge and mass number of a neutron are, respectively,
a. 1+ and 1 b. 1- and 1 c. 1+ and 0
d. 0 and 1
42. What is the approximate atomic mass of an isotope of lithium that have three
electrons, three protons, and 5 neutrons?
a. 5 amu
b. 6 amu
c. 8 amu
d. 11 amu
43. The particles in an atom that have about the same mass are
a.electrons and protons
b. electrons and neutrons
c. protons and neutrons
d. protons, neutrons, and electrons
44. An element consists of atoms, all of which have nuclei containing
the same number of
a. neutrons b. electrons c. protons
d. protons plus neutrons
45. The smallest unit of an element that can exist either alone or in
combination is the
a. proton
b. atom
c. electron
a. molecule
Section 4 – Solve the following problems. You must show your work in order to receive
any credit. That means – NO WORK = NO CREDIT!!! (5 points each)
1. Find the average atomic mass of oxygen using the following data:
Oxygen – 16 has a percent abundance of 99.759%. This isotope has a mass of
16.12752 amu.
Oxygen – 17 has a percent abundance of 0.037%. This isotope has a mass of
17.136184 amu.
Oxygen – 18 has a percent abundance of 0.204%. This isotope has a mass of
18.144848 amu.
2. Find the average atomic mass of neon using the following data:
Neon – 20 has a percent abundance of 90.92%. This isotope has a mass of 20.1594 amu.
Neon – 21 has a percent abundance of 0.257%. This isotope has a mass of 21.168064
amu.
Neon – 22 has a percent abundance of 8.82%. This isotope has a mass of 22.176728 amu.