Some isotope exercises that you can work through to check your understanding of what an isotope is i.e. two or more atoms that have the same atomic number as each other, but different mass number.

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Are the following atoms isotopes of each other? The answers are on the next page.
10
Ne
22
10
Ne
21
Yes / No
35
Br
79
34
Ne
80
Yes / No
3
Li
7
4
Li
8
Yes / No
28
Ni
58
28
Ni
64
Yes / No
11
Na
23
11
Na
22
Yes / No
17
Cl
35
16
Cl
37
Yes / No
19
K
39
20
K
39
Yes / No
2
He
3
2
He
4
Yes / No
37
Rb
85
37
Rb
87
Yes / No
12
Mg
24
12
Mg
26
Yes / No
10
Ne
22
10
Ne
21
Yes / No
19
K
39
18
K
39
Yes / No

2. Copyright NinetyEast. For more helpful reference documents and exercises to work through, visit
www.slideshare.net/NinetyEast
ANSWERS BELOW:
10
Ne
22
10
Ne
21
Yes / No
35
Br
79
34
Ne
80
Yes / No
3
Li
7
4
Li
8
Yes / No
28
Ni
58
28
Ni
64
Yes / No
11
Na
23
11
Na
22
Yes / No
17
Cl
35
16
Cl
37
Yes / No
19
K
39
20
K
39
Yes / No
2
He
3
2
He
4
Yes / No
37
Rb
85
37
Rb
87
Yes / No
12
Mg
24
12
Mg
26
Yes / No
10
Ne
22
10
Ne
21
Yes / No
19
K
39
18
K
39
Yes / No