1. 1. The concept of positive charge and a small,
“heavy” nucleus surrounded by electrons
was the contribution of
Dalton
Rutherford
(c) Thomson
(d) Chadwick

2. 1. The concept of positive charge and a small,
“heavy” nucleus surrounded by electrons
was the contribution of
Dalton
Rutherford
(c) Thomson
(d) Chadwick

3. 2. An atom of atomic number 53 and mass
number 127 contains how many neutrons?
(a) 53
(b) 74
(c) 127
(d) 180

4. 2. An atom of atomic number 53 and mass
number 127 contains how many neutrons?
(a) 53
(b) (127-53)
(c) 127
(d) 180

5. 3. How many electrons are in an atom of 4018Ar ?
(b) 22
(c) 40
(d) no correct answer given

6. 3. How many electrons are in an atom of 4018Ar ?
(b) 22
(c) 40
(d) no correct answer given
(neutral, p = e- = 18)

7. 4. The number of neutrons in an atom of
139 56Ba is
(a) 56
(b) 83
(c) 139
(d) no correct answer given

8. 4. The number of neutrons in an atom of
139 56Ba is
(a) 56
(b) (139-56)
(c) 139
(d) no correct answer given

9. 5.The name of the isotope containing
one proton and two neutrons is
(a) protium
(b) tritium
(c) deuterium
(d) helium

10. 5. The name of the isotope containing
one proton and two neutrons is
(a) protium 11H
(b) tritium 31H
(c) deuterium 21H
(d) helium

11. 6. Each atom of a specific element has the same
(a) number of protons
(b) atomic mass
(c) number of neutrons
(d) no correct answer given

12. 6. Each atom of a specific element has the same
(a) number of protons (atomic #)
(b) atomic mass
(c) number of neutrons
(d) no correct answer given

13. 7. Which pair of symbols represents isotopes?
(a)2311Na and 2312Na
(b) 73Li and 63Li
(c) 63 29Cu and 2964Cu
(d) 1224Mg and 1226Mg

14. 7. Which pair of symbols represents isotopes?
(a)2311Na and 2312Na
(b) 73Li and 63Li
(c) 63 29Cu and 2964Cu
(d) 1224Mg and 1226Mg

15. 8. Two naturally occurring isotopes of an
element have masses and abundance as
follows: amu (20.00%) and
56.00 amu (80.00%). What is the
relative atomic mass of the element?
(a) 54.20
(b) 54.40
(c) 54.80
(d) 55.60

16. 8. Two naturally occurring isotopes of an
element have masses and abundance as
follows: amu (20.00%) and
56.00 amu (80.00%). What is the relative
atomic mass of the element?
(a) 54.20
(b) (.2000) = 10.80
(c) (.8000) = 44.80
(d)

17. 9. Substance X has 13 protons, 14 neutrons,
and 10 electrons. Determine its identity.
(a) 27Mg
(b) 27Ne
(c) 27Al3+
(d) 27Al

18. 9. Substance X has 13 protons, 14 neutrons,
and 10 electrons. Determine its identity.
(a) 27Mg
(b) 27Ne
(c) 27Al3+
(d) 27Al

19. 10.The number of neutrons in an atom of
10847Ag is
(a) 47
(b) 108
(c) 155
(d) no correct answer given

20. 10. The number of neutrons in an atom of
10847Ag is
(a) 47
(b) 108
(c) 155
(d) no correct answer given
(108 – 47 = 61)

21. 11. The number of electrons in an atom of
2713Al is
(a) 13
(b) 14
(c) 27
(d) 40

22. 11. The number of electrons in an atom of
2713Al is
(a) 13 (neutral, p = e- = 13)
(b) 14
(c) 27
(d) 40

23. 12. The number of protons in an atom of
6530Zn is
(a) 65
(b) 35
(c) 30
(d) 95

24. 12. The number of protons in an atom of
6530Zn is
(a) 65
(b) 35
(c) 30
(d) 95

25. 13. The number of electrons in the nucleus of
an atom of 2412Mg is
(a) 12
(b) 24
(c) 36
(d) no correct answer given

26. 13. The number of electrons in the nucleus of
an atom of 2412Mg is
(a) 12
(b) 24
(c) 36
(d) no correct answer given

27. Free Response Questions
14. What is an ion?

28. Free Response Questions
14. What is an ion?
An ion is a charged atom or group of atoms.
The charge can be either positive
(“cation” - resulting from a loss of e-)
or negative
(“anion” – resulting from a gain of e-).

29. 15. The average mass of a calcium atom is
40.08 amu. Why do we also use amu
as the average mass of a calcium ion (Ca2+ )?

30. 15. The average mass of a calcium atom is
40.08 amu. Why do we also use amu
as the average mass of a calcium ion (Ca2+ )?
Electrons have negligible mass compared
to the mass of protons and neutrons. The
only difference between Ca and Ca2+ is two
electrons. The mass of those two electrons
is insignificant compared to the mass of the
protons and neutrons present (and whose
numbers do not change).