Download Isotopes and Ions

Isotopes and Ions
Fill in the following table:
Symbol Atomic
Mass
23
Na
Ne
Hg
Zn
Al
11
20
10
201
80
65
30
27
13
Atomic # of
Number protons
# of
# of
neutrons electrons
Fill in the following table:
Symbol
Atomic Atomic # of
# of
# of
Mass Number protons neutrons electrons
127
Cd
2+
53
54
112
38
2-
X
3+
X
103
50
36
75
54
42
What is an Ion?
An atom that is positively or negatively
charged
 An atom that is positively charged has ____
electrons than the number of protons
 An atom that is negatively charged has ____
electrons than the number of protons

What is an Isotope?
Atoms of the same element that contain
different numbers of neutrons
 Example:
 Nitrogen has two isotopes: Nitrogen-14
(14N) and Nitrogen-15 (15N)
 Nitrogen 14 has _________ neutrons
 Nitrogen 15 has _________ neutrons

Determining the average atomic
mass
The average atomic mass (m) of an element depends on the
proportions of the isotopes.
Sample 1:
10B = 18.8%
11B = 81.2%
Average = (% 10B)(mass of 10B) + (%11B)(mass of 11B)
= (0.188)(10) + (0.812)(11)
= 1.88 + 8.982
= 10.812 m
The average atomic mass for Boron is 10.812 m
Determine the % of each isotope
Given the average atomic mass and the isotopes present in
the mixture, the % of each isotope present can be calculated.
Example: Calculate the % of each isotope present in the mixture
of 107Ag and 109Ag that has an average mass of 107.9 m.
Let x represent 107Ag and (1-x) represent 109Ag
107 x + 109 (1 – x) = 107.9
107 x + 109 – 109 x = 107.9
2 x = 1.1
x = 0.55
1 – x = 0.45
Therefore 107Ag = 55% and 109Ag = 45%