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AGN – Ions & Isotopes
Name _________________________________
Part I. Complete the following table.
1)
Atomic
Mass
Number
Number
12
24
Protons
Neutrons
Electrons
Symbol
12
12
12
24
Mg
12
2)
39
19
20
19
19
39
K
19
3)
30
66
30
36
30
66
Zn
30
4)
35
80
35
45
35
80
Br
35
5)
79
197
79
118
79
197
Au
79
6)
8
16
8
8
10
16
O2-
8
7)
13
27
13
14
10
27
Al+3
13
8)
19
39
19
20
18
39
K+
19
9)
54
25
25
29
21
54
Mn4+
25
10)
15
31
15
16
18
31 3-
P
15
Part II. Base on these sketches, fill in the table. Solid circles represent protons, open circles represent
neutrons. Then, identify the elements shown above in the diagrams; include their mass number (ex.
Carbon-14).
Atom
Protons Neutrons
Electrons
Atomic
Mass
(not shown)
Number Number
Name – Mass number
A
3
3
3
3
6
Lithium – 6
B
4
4
4
4
8
Beryllium – 8
C
3
4
3
3
7
Lithium – 7
D
5
4
5
5
9
Boron – 9
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AGN – Ions & Isotopes
18) Two of the atoms sketched are the same element. Which two atoms? (Give names not letters)
Lithium – 6 and Lithium – 7
19) Atoms of the same element that have different mass numbers are called ___isotopes____________
20) In each atom shown, how do the numbers of protons and the number of electrons compare?
Protons equal electrons.
21) Why is an atom said to be “electrically neutral?”
Positive protons equal negative electrons.
22) If an atom has a charge of 2+, has it lost 2 electrons or gained 2 electrons? Explain.
The atom has lost two electrons; so it has two more positive protons than negative electrons.
23) Atoms of the same element that have different charges are called ____ions________________
Part II. Answer the following questions.
24) Explain how the isotopes of one element are alike and how they are different. Give at least two
examples of each.
Isotopes have the same number of protons and the same atomic number, but they have different
mass numbers and different numbers of neutrons.
25) What does a..m.u. stand for?
Atomic mass unit
26) The element Argon has three naturally occurring isotopes. The relative abundances are 0.337%,
0.063% and 99.600% respectively. Calculate the average atomic mass of argon. SHOW YOUR
36
38
40
WORK!
Ar
Ar
Ar
18
18
18
39.95 a.m.u.
27) There are three isotopes of carbon: carbon-12, carbon-13, and carbon-14. The atomic mass of
carbon is 12.01 a.m.u. Comment on the relative abundance of these three isotopes.
Carbon-12 must be the most abundant.
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