Protons, Neutrons, and Electrons Practice Worksheet
Fill in the blanks in the following worksheet. Please keep in mind that the isotope
represented by each space may NO T be the most common isotope or the one closest in
atomic mass to the value on the periodic table.
Atomic
symbol
Atomic
number
B
tJ(Jv
GrA
o
11
31
Y
3~
3~
Tc.,
29
43
&
-
I
I
.Mass
Number
Protons
Neutrons
Electrons
D
6
V
II
13
H
II
24
31
3{
bg
2~
37
5D
35
43
51
4-3
39
Zq
89
(of
Pb
r2..
~1-
125
g2..
100
207
Yb
11J
10-
102
70
)'1-2-
84
89
42
1310
gt1
225
53
is"'
~\
12-5
\(1)
4181
159
1O""D
101-
15'1
101-
\ {) 1-
11J
A(;
Mo
f\M
4281
100
No
I ()'1-
Yb
-t»
0C\.\)
lo~
-rl
I
~
106
159
1() (p
206
2S1
261
172
2lpS-
3
1.
Determine the number of protons, neutrons, and electrons present in each of
the following atoms.
e
2.
I~
I~
b)
197Au
79
l\?
c) 4°Ar
18
d) Cu-64
e)
K-39
3.
sS
55
e) Cs-133
Represent the following isotopes in two different ways.
b) 53p +, 53e-, 68no
f-I~I
\~I
4. 3. Identify atoms that are isotopes in each of the following
20X
8
_~~
c)
iSb~
~
Fluov\'~
sets of four
Atomic Mass Problems
1.
Calculate the weight of silicon using the following data for the percent natural abundance and mass of each
isotope:
92.23% :::sSi(27.9769 amu); 4.67% :9 Si (28.9765); 3.10% 30Si (29.9738 amu).
)7-9%q J( D,Q;;-J-3:;- J~(g-030rt.{g1
J-B-. 1tis: x. 0,04111- =
L 35""' }-O;t-_n2-1.1138- )( O;03l'D' +-0, q?f1/ f(f(
2.
~ ~
.
.
'0'
~o,
Thallium has two stable isotopes, -'~Tl an - "Tl.
\\'hi:h isotope is the more abundant of the two.
US
---1t--")
WO'fI-lJ.
k~i.
Th ~
~~
rs J/1N~~cJ_
~
~
Iji.01eIght~7.
. 204.4,
of tlJUium
.'~
towing that the a~
,
1S
\I
'
e~~h)
:r:t~'(i)~\.AI~~.f,oI1
~~
.
_/)
~~(C~'l
+u, ~w-~
j:.s ~reo-iZv~
u4-.J
vwn. ()..~c:Lt,._+-\~"hre"+lUJS-.
if
Z~, q~y2.
2L{t
q 8's-f3?-
X-
J(
>=
o.}lol
25<182.--~3X
J f ~f1Y):;~ YW
s. Lf q l("5"f 2J 1-
0,7011
o.t»r»>
""to('~o~
?7-tJ1
L?~b5Ia~i}_
4.
Copper exists as two isotopes: 63CU(62.9298 amu) and
What are the percent abundances of the isotopes?
Abtwltlt\M.U,
lA
65eu
(64.9278 amuj.L,
1u-~:1 X
C4 -~ s-~I-X
s:
11
.;Fom/+
~t-9Vl8
X
+
h4, fl1't (I-X)
~2.qtq8 X + (p,-+. q~ 7& -
::: ~3.9+"
(pL(-.
q~T~)(
.?
-I, Q9KO)(
/lJDJ<
X
lOa --x
-
fo3S'fbO
-I, 3~{f
,-q_~1t ~
:=
:!:
30 ( rr-t(J~
(0
Transmutation
Name:
_
Transmutation is the process of converting one element into another (using bombardment
with high energy particles). The target nucleus is the isotope which is bombarded, the
projectile is the particle fired at the nucleus, the product is the new nucleus produced by
the reaction, and the ejected particle is the light nucleus or particle emitted in the
reaction. This bombardment takes place in a particle accelerator (cyclotron, synchrotron,
linac, etc.). Many.of the radioactive products of nuclear bombardment are useful in
medicine and industry as tracers, etc ..
Part 1: Fill in the blank in each transmutation reaction with the correct particle, and
label each particle as the target, projectile, product, and ejected particle.
1.
14N + 4He
7
2.
1
i~&
27AI
+
------->
13
3.
12C -------->
246Cm +
96
4.
6.
27
qt-M
4-2..
IQi
'f
+
2H
1
l =197
Tc +
------------->
---------->
239U
In
+
~At
----------> 238Np
92
93
0
---------->
ft Co.+
In
0
-1e
0
In +
4
C0
~o
--------->
(J¥e_
0
98Mo + In
0
( -t1u-rt.
+ 4 In
43
4He
,
42
10.
N0
'254
0
2
7.
9.
In
0+ 1 H
209Bi +
8.
In
0
:::70
1
83
30P +
15
6
59Co +
5.
Il D
+
IH
-------->
2
~ ~~
--------->
0
qq
it'3
+
40K +
+ 2 In
IH
19
---------->
4He
2
+
IH
1
1l
V
C2-~~)
V\.W-~
c )
Part 2: Rewrite the following reactions in symbol form:
11) A neutron hits a uranium-235 atom, splitting it into a barium-140 atom, a krypton-93
atom and 3 neutrons.
+
+
12) A zirconium-95 atom undergoes beta decay to become stable.
13) A cobalt-59 nucleus is bombarded by a neutron to roduce cobalt-60.
14) An iron-58 is hit by a bismuth-209 nucleus to form meitnurium-266 and a neutron.
15) A molybdenum-96 atom is hit by deutrium (hydrogen-2) to form technetium-97 and a
neutron.
Part 3: Determine the product nucleus of the following reactions:
16) A curium-246 nucleus is hit by a carbon-12 atom to produce what product nucleus and
4 neutrons?
17) A lead-218 atom decomposes by alpha decay to produce what new nucleus?
18) A neutron is fired at a uranium-235 atom, where the atom splits apart into what
product atom along with zirconium-97 and 2 neutrons?
q1
2v
40
T
1-
2
I
131-'1.
0 V\ -\- 52- Ie.
J_
2-
-
Ib
~
'+
2/),/f('
I
I
I
~
51z.
I~
/OV/
Half-life Practice Worksheet
1. Sodium-24 has a half-life of 15 hours. How much sodium-24 will remain in an
18.0 9 sample after 60 hours?
x - _...------I
l~~t~:1ft~ ~~J_1r'\
~ .. A
~Ih'£tt
J)..
I~
10
Je-~~oh
.
{,t-=. 15'1-1
2. After 42 days a 2.0 9 sample of phosphorus-32 contains only 0.25 9 of the
isotope. What is the half-life of phosphorus-32?
1t1(hPL -:::2.'01
{lVtlli 7 ....
o'zs-~
f-r
ao
4z_J
':=-
alas- :
.,
1
s ~
j_ ~
t'/t;
3. Polonium-214 has a relatively short half-life of 164 seconds. How many
seconds would it take for 8.0 9 of this isotope to decay to 0.25 g?
) ~I .f-j"'a..t ;:
8"( 0 "r
O.2S~
C>.U'_
~I~---
" -
~..L .j h
g cr
j'l;-=-
t (h. l~y_ ";)
32
V1=-S"
2-
TEo:;:. VI
-= S X I (p Lf
-=--
4. How many days does it take for 16 9 of palladium-1 03 to decay to 1.0 g? The
. half-life of palladium-1 03 is 17 days.
\VII ~
fi VloJ"
~
{~,--
~
_j_ ;;; J_
ll?
2-
I~
~ri'-~
ty2. ~
ot II)_..
t:
~g-20
A._
V\::: \'
\'=f·d.
5. By approximately what factor would the mass of a sample of copper-66
decrease in 51 minutes? The half-life of copper-66 is 5.10 minutes.
,~,h~ ::
VVlJJ.. -;;.
Yl.,..
-re: -::.51
-f/'},:-
,
WIll'!
5. I 0
~I
~
6. In 5.49 seconds, 1.20 9 of argon-35 decay to leave only 0.15 g. What is the
half-life of argon-35?
I~I~~ " l,
f>~'
n
l02:
0.\
t
D·I:S-
-;.
5- '-Iq~
1(:: .._
t/~::
\ £" _ t \( -
V\
-v
1- -
r
~
5~0'- - 0 , 108'b-S
'-----;-
t
HALF-LIFE PROBLEMS
Name
Block
----------------------------------
a
------
1. An isotope of cesium (cesium-137) has a half-life of 30 years. If 1.0 g of cesium-137
disintegrates over a period of 90 years, how many g of cesium-137 would remain?
I~H'~~ \t
hVid ~
V\
:
~
3-;::.
I
(3
-.. qo
.3
..--l)<
~
) ~1
_---J--
«.___
1--
0, l~'0 \
2~1~tin&~'k26 has a half-life of 29 hours. If 100 mg of actinium-226 disintegrates over a
period of 58 hours, how many mg of actinium-226 will remain?
\ V\
I
too~
t-Ia..Q__ ::
~ .:t~
~~~
_': )Z.
2~
:::
\Dl)~~
Ix ~Z':) ~/
(l-\ ~ ..L
l2-)
J
L\- ~
+-,1, ~ 2-q L\ ("".
3. Sodium-25 was to be used in an experiment, but it took 3.0 minutes to get the sodium
from the reactor to the laboratory. If 5.0 mg of sodium-25 was removed from the reactor,
how many mg of sodium-25 were placed in the reaction vessel 3.0 minutes later if the halflife of sodium-25 is 60 seconds?
4 I'" tt-u. ~ .
I
\~fto..l;; 5~O~
~
'6
~--'7
\C0lo 3~t';
-h~;
V\
L
3
-.
-rc ... :3~
\l
VI
{~"\ 1~
>
501V\
.
1..-)
~
--L'f'l- -:. ~ 0 s.
4. The half-life of isotope X is 2.0 years. How many years would it take for a 4.0 mg sample
of X to decay and have only 0.50 mg of it remain?
il1"hAQ ~ +0 ~
~~~
V1
..
D'S""1\
b
-:
T~ -;:.
t'fz-;:- Z 10 lir
5. Selenium-83 has a half-life of25.0 minutes. How many minutes would it take for a 10.0
mg sample to decay and have only 1.25 mg of it remain?
,V\,h'-~'"
\D~
Jt,~._
\,2-
C
\(zs-~)
~
;,,, ~
I0
."
t\
2--
1
7
IS
~::
?
i;
L'
.3 x z<;,..,'. ;: ~
ltV1---;: 2-5rOvt<~
6Frthe half-li:(eofPo-2l8 is three minutes. How much ofa 2.0 gram sample remains after
15 minutes?yt3uppose you wanted to buy some of this isotope, and it required half an hour
for it reach you. How much should you order if you need to use 0.10 gram of this
frrnate~ial~
\t'\I.f1~
t\vW.9-
.
5
n:: \'1~I~'
t l/'l,,:; -3 i~,;'_
k~X
z
~_L2)b
_'X ~ - I
2.
32-
I
•
(X ::: OrOCo
.
3
?=/
y-
It- ~qO~I~
1:{'1- -;.
3 10'1;'
;'\==- 30
-