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Chemistry
Worksheet : Ch. 4-6; Obj. 1-9
Name :
Date :
A. Read pp. 101-130 and answer the following questions :
1. __________________ are the smallest particles of an element which retain the properties of that element.
2. __________________ was the English chemist who first established the atomic theory in the late 1700's.
3. Put a check next the following statements of Dalton's atomic theory which are correctly written. If the
statement is written incorrectly change it so that it is correct.
_____ All compounds are made up of tiny indivisible particles called atoms.
_____ Atoms of the same element are identical. Atoms of any one element are different from those of other
elements.
_____ Atoms of different elements can combine in any ratio with one another to form compounds.
_____ Chemical reactions occur when atoms are separated, joined or rearranged. Atoms of an element may also
be changed into atoms of another element.
4. Match the characteristics of the subatomic particles (Choose all correct answers) :
_______ electrons
_______ protons
_______ neutrons
a. positively charged
b. negatively charged
c. neutral (no charge)
d. have a mass of one a.m.u.
e. have a mass of 1/1840 a.m.u.
f. orbit the nucleus
g. found in the nucleus
h. discovered by Sir J.J. Thomson
i. discovered by Sir James Chadwick
5. _____(T/F) A cathode ray is a glowing beam which travels from the anode(positively charged pole) to the
cathode(negatively charged pole)
6. List three observations Thomson made using the cathode ray tube which helped him discover electrons and
their characteristics.
7. Explain how Ernest Rutherford discovered the existence of the nucleus of an atom and what specific
observations led him to suppose the existence of the nucleus.
8. _____(T/F) The nucleus of an atom occupies much of the space(volume) of an atom.
9. _____(T/F) The electrons make up most of the mass of an atom.
10. The ___________________ of an element is the number of protons in an atom of that element and defines the
element.
11. The __________________ of an element indicates the total number of neutrons and protons in the nucleus of
an atom of that element
12. _____ (T/F) The mass number of an element may be a fraction.
13. ____________________ are the units used to measure the mass of atoms and are equal to one-twelfth the
mass of a carbon atom that has six protons and six neutrons.
14. ___________________ are atoms of the same element which have a differing number of neutrons.
15. Label the following diagram of the element sodium
_____ atomic mass
_____ atomic number
_____ element symbol
11
Na
22.99
a.
b.
c.
16. Answer the following for sodium from the above information
_____ number of protons
_____ number of neutrons
_____ number of electrons
17. _____ (T/F) Isotopes will have the same mass number.
18. _____(T/F) Isotopes will have the same atomic number.
19. Complete the following table :
A
t
o
m
i
c
n
u
m
b
e
r
M
a
s
s
N
u
m
b
e
r
N
o
.
o
f
p
r
o
t
o
n
sN
o
.
o
f
n
e
u
t
r
o
n
s
N
o
.
o
f
e
l
e
c
t
r
o
n
s
S
y
m
b
o
l
o
f
e
l
.
8
8
3
2
1
6
1
3
2
7
1
9
2
0
20. Match the model of the atom with the person who proposed the model or its name.
_____ Rutherford's model
_____ Dalton's model
a.
b.
_____ Bohr's model
_____ Thomson's model
c.
d.
_____ Quantum mechanical model
region w here there is 90%
probability of finding electrons
e.
21. _____(T/F) The discovery of subatomic particles shattered Dalton's theory of the structure of atoms.
22. _____(T/F) The Bohr model of the atom is the most accepted model today.