1. End Show © Copyright Pearson Prentice Hall Distinguishing Among Atoms > Slide 1 of 52 Atomic Mass How do you calculate the atomic mass of an element? 4.3

2. End Show Slide 2 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms Atomic Mass It is useful to to compare the relative masses of atoms to a standard reference isotope. Carbon- 12 is the standard reference isotope. Cabon-12 has a mass of exactly 12 atomic mass units. An atomic mass unit (amu) is defined as one twelfth of the mass of a carbon-12 atom. 4.3

3. End Show Slide 3 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms Atomic Mass Some Elements and Their Isotopes 4.3

4. End Show Slide 4 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms Atomic Mass The atomic mass of an element is a weighted average mass of the atoms in a naturally occurring sample of the element. A weighted average mass reflects both the mass and the relative abundance of the isotopes as they occur in nature. 4.3

5. © Copyright Pearson Prentice Hall Slide 5 of 52 End Show

6. © Copyright Pearson Prentice Hall Slide 6 of 52 End Show Practice Problems for Conceptual Problem 4.3

7. End Show Slide 7 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms Atomic Mass For example, carbon has two stable isotopes: Carbon-12, which has a natural abundance of 98.89%, and Carbon-13, which has a natural abundance of 1.11%. 4.3 To calculate the atomic mass of an element, multiply the mass of each isotope by its natural abundance, expressed as a decimal, and then add the products.

8. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 8 of 52 End Show 4.2

9. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 9 of 52 End Show 4.2

10. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 10 of 52 End Show 4.2

11. © Copyright Pearson Prentice Hall Slide 11 of 52 End Show Practice Problems for Sample Problem 4.2

12. End Show Slide 12 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview A periodic table is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties. A periodic table allows you to easily compare the properties of one element (or a group of elements) to another element (or group of elements). 4.3 The Periodic Table—A Preview Why is a periodic table useful?

13. End Show Slide 13 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview The Periodic Table 4.3

14. End Show Slide 14 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview Each horizontal row of the periodic table is called a period. Within a given period, the properties of the elements vary as you move across it from element to element. 4.3

15. End Show Slide 15 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview A Period 4.3

16. End Show Slide 16 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview Each vertical column of the periodic table is called a group, or family. Elements within a group have similar chemical and physical properties. 4.3

17. End Show Slide 17 of 52 © Copyright Pearson Prentice Hall > Distinguishing Among Atoms The Periodic Table—A Preview A Group or Family ( Groups 1-18 regents tables) 4.3

18. End Show © Copyright Pearson Prentice Hall Slide 18 of 52 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 4.3 Section Quiz 4.3.

19. © Copyright Pearson Prentice Hall Slide 19 of 52 End Show 4.3 Section Quiz 1. Isotopes of an element have a.the same mass number. b.different atomic numbers. c.the same number of protons but different numbers of neutrons. d.the same number of protons but different numbers of electrons.

20. © Copyright Pearson Prentice Hall Slide 20 of 52 End Show 4.3 Section Quiz 2. How many neutrons are in sulfur-33? a.16 neutrons b.33 neutrons c.17 neutrons d.32.06 neutrons

21. © Copyright Pearson Prentice Hall Slide 21 of 52 End Show 4.3 Section Quiz 3. If sulfur contained 90.0% sulfur-32 and 10.0% sulfur-34, its atomic mass would be a.32.2 amu. b.32.4 amu. c.33.0 amu. d.35.4 amu.