Review Questions – Chapter 4
1. Which scientist's theory about the atomic model had the following?
1.
2.
3.
4.
5.
Defined atoms as indestructible?
Atoms of different elements can combine in whole-number ratios?
The atom contained a small dense positive center.
The atom contained particles of negative charge.
Due to the mass in the nucleus being much greater there was a neutral particle
with a mass equal to the proton.
2. Why were Dalton's ideas more believable than Democritus?
3. Who is given credit for discovering the electron?
4. What justification did Thomson have for all atoms having electrons?
5. Goldstein (pg. 106) is credited for finding the proton in an atom. What is the charge
on a proton?
6. Negatively charged subatomic particles are known as...
7. The tiny central core of an atom that is composed of protons and neutrons is the .....
8. Draw the atomic model of Dalton. of Thomson... of Chadwick ...of Rutherford
9. Which subatomic particles have the same mass?
10. Why is the atom mostly empty space?
11. What part of Dalton's theory did Thomson disprove?
Use a periodic table to answer the following questions:
12. What is the atomic number for:



Kr
Mg
Pt
13. How many protons are in an atom of



Se
Mercury
cesium
14. How is the number of neutrons calculated in any atom?
15. The mass number is composed of which subatomic particles?
16. How many neutrons are in O-16?
17. Give the number of protons, neutrons, and electrons for Ag-108
18. One-twelfth of the mass of a carbon-12 atom is called -----19. The weighted average mass of the atoms in a naturally occurring sample of the
element is called the _________________.
20. Atoms with the same atomic number but different mass numbers are known as
____________________________.
21. Which subatomic particle identifies an atom?
Symbol
#proton
#neutrons
31
38
52
75
#electrons
Charge
Pb-206
Mn
29
ANSWERS:
1.
1.
2.
3.
4.
5.
Democritus
Dalton
Rutherford
Thomson
Chadwick
2. He could support his theories with experimental evidence
3. Thomson
4. Any gas he used produced the same mass to charge ratio
3+
54
2+
5. positive
6. electrons
7. nucleus
8.
9. proton and neutron
10. The majority of the alpha particles passed straight through the gold foil
11. Atoms are indivisible (With the discovery of the electron we now know they are
divisible)
12.



36
12
78



34
80
55
13.
14. Mass number - atomic number
15. protons and neutrons
16. 8
17. 47, 61, 47
18. atomic mass unit
19. atomic mass
20. isotopes
21. proton
Symbol
#proton
#neutrons
#electrons
Charge
Pb-206
82
124
82
0
Ga3
31
38
28
3+
Te 2
52
75
54
2-
Mn 2 
25
29
23
2+
69
31
127
52
54
25