Isotipes and atomic mass

Chapter 4 Atoms and
Elements
4.5
Isotopes and Atomic Mass

1

Basic Chemistry

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Isotopes
Isotopes

• are atoms of the same element that havedifferent mass numbers
• have the same number of protons, but different
numbers of neutrons

2

Basic Chemistry

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Nuclear Symbol
A nuclear symbol• represents a particular atom of an element
• gives the mass number in the upper left corner
and the atomic number in the lower left corner

Example: An atom of magnesium with an atomic
numberof 12 and a mass number of 24 has the
following atomic symbol:

3

Basic Chemistry

Copyright © 2011 Pearson Education, Inc.

Information from Nuclear
Symbols
• The nuclear symbolindicates the number of
protons (p+), neutrons, (n), and electrons (e-) in
a particular atom.
16

31

8

15

8 p+
8n
8 e-

15 p+
16 n
15 e-

O

4

Basic Chemistry

P

65
30

Zn30 p+
35 n
30 e-

Copyright © 2011 Pearson Education, Inc.

Learning Check
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons,and electrons in each of the
following.
12C

6

13C

14C

6

6

protons

______

______

______

neutrons

______

______

______

electrons ______

______

______5

Basic Chemistry

Copyright © 2011 Pearson Education, Inc.

Solution
Naturally occurring carbon consists of three
isotopes, 12C, 13C, and 14C. State the number of
protons, neutrons, andelectrons in each of the
following.
12C

13C

14C

6

6

6

6 p+

6 p+

neutrons 6 n

7n

8n

electrons 6 e-

6 e-

6 e-

protons

6

Basic Chemistry

6 p+Copyright © 2011 Pearson Education, Inc.

Learning Check
Write the nuclear symbols for atoms with the
following subatomic particles:
A. 8 p+, 8 n, 8 eB. 17 p+, 20 n, 17e-

___________

C. 47 p+,...