Name: Gavenjit Dhesi
Block:
Mrs.
Wong
Isotope Quiz
1.
2.
Here are three isotopes of an element:
312
A<
a.
The element is: Argon
b.
The number 18 refers to the Atomic number
c.
The numbers
d.
How many protons and neutrons are in the first isotope? 18 protons and 18 neutrons (36-18 = 18)
e.
How many protons and neutrons are in the second isotope? 18 protons and 20 neutrons (38-18 = 20)
f.
How many protons and neutrons are in the third isotope? 18 protons and 22 neutrons (40-18 = 20)
Com
36, 38,
lete the followin
and 40 refer to the The mass number
chart:
Isotope
Isoto e
symbol
name
atomic #
mass #
19
37
17
35
# of
rotons
# of
neutrons
# of
electrons
Potassium-37
chlorine-35
uranium-235
238
uranium-238
92
235
92
238
5
10
12
26
boron-10
Magnesium-26
17
92
12
18
18
146
92
14
10
DIRECTIONS: For the following problems, show your work! (5 pts each)
3.
Sulfur consists of four isotopes with masses of 32 (abundance 94.93%), 33 (abundance of 0.76%),
(abundance of 4.29%), and 36 (abundance of 0.02%). Calculate the atomic mass of sulfur.
(32 x 94.93) + (33 x 0.76) + (34 x 4.29) + (36 x 0.02)
-------------------------------------------------------------100
= the atomic mass of sulfur is 32.09 (32.0942 rounded is 32.09)
3,037.76 + 25.08 + 145.86 + 0.72
---------------------------------------100
3,209.42
----------100
34
46
4.
47
common isotopes: nTi (8.0%), 22Ti (7.8%), æTi (73.4%),
49Ti (5.5%), 9}Ti (5.3%). What is the average atomic mass of titanium?
Titanium has
five
46 x .08 = 3.68
47 x .078 = 3.666 -> 3.67
48 x .734 = 35.232 -> 35.23
= 47.92 is the average atomic mass of titanium
49 x .055 = 2.695 -> 2.70
50 x .053 = 2.65
47.923 -> 47.92
5.
Boron exists in two isotopes, boron-10 and boron-II. Based on the atomic mass, which isotope should
be more abundant?
n,
The atomic mass of boron is 10.81 u. 10.81 u is much more closer to 11u compared to
10 u, therefore, there has to be more of boron-11.
Solving for X:
11u - ux = 10.81u
0.19u = ux
x = 0.19
1 - x = 0.81
(10u)(x) + (11u)(1 - x)
---------------------------- = 10.81 u
100%
U is the unit for atomic mass
X is the proportion of boron-10 out of the total boron abundance
which is 100%
Boron-11 is much more abundant.
As a result, the abundance of boron-11 is 81%, roughly.