1. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 The Modern View of Atomic Structure l electrons l protons: found in the nucleus, they have a positive charge equal in magnitude to the electron’s negative charge. l neutrons: found in the nucleus, virtually same mass as a proton but no charge. The atom contains:

2. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 2 Figure 2.14 Nuclear Atom Viewed in Cross Section

3. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 3 The Mass and Change of the Electron, Proton, and Neutron

4. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 4 ATOMS Very dense nucleus containing almost all of the atom’s mass. Electrons constitute most of the volume of the atom. Electrons are involved when atoms combine or “bond” to form molecules. All atoms contain protons, electrons and neutrons

5. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 5 ATOMS Different atoms have different properties due to different #’s of protons, electrons and neutrons. Atomic number (Z) = # of protons Mass number (A) = # of protons + # of neutrons

6. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 6 ISOTOPES Atoms with the same # of protons but different # of neutrons. Isotopes have almost identical chemical properties since they have the same # of electrons.

7. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 The Chemists’ Shorthand: Atomic Symbols K  Element Symbol 39 19 Mass number  Atomic number 

8. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 Figure 2.15 Two Isotopes of Sodium

9. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 The Chemists’ Shorthand: Formulas Chemical Formula: Symbols = types of atoms Subscripts = relative numbers of atoms CO 2 Structural Formula: O=C=O

10. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 ION Atoms or groups of atoms that has a net positive or negative charge. Atoms either gain or lose electrons to acquire a charge.

11. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Ions Cation: A positive ion Mg 2+, NH 4 + Anion: A negative ion Cl , SO 4 2  Ionic Bonding: Force of attraction between oppositely charged ions. Salt (Ionic solid): Solid consisting of oppositely charged ions.

12. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 Figure 2.19 Sodium Chloride

13. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 13 IONS Simple Ions: Na + Cl - Al 3+ N 3- Polyatomic Ions: Groups of covalently bonded atoms that carry a charge. NH 4 + CO 3 - NO 3 - NO 2 -

14. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 Periodic Table Elements classified by:  properties  atomic number Groups (vertical) 1 or 1A = alkali metals 2 or 2A = alkaline earth metals 17 or 7A = halogens 18 or 8A = noble gases Periods (horizontal)

15. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Alkali Metals Group 1 or Group 1A

16. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Alkali Metals Group 1 or 1A Metals with low mp Soft enough to cut with a knife Form +1 ions when reacting with non- metals

17. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17

18. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18 Alkaline Earth Metals Group 2 or 2A Less reactive than Group 1 Form +2 ions when reacting with non-metals

19. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 19

20. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 20 Halogens Group 17 or 7A or VII A Non-metals Form -1 ions when reacting with metals

21. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 21

22. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 22 Noble Gases Group 18 or Group 8A

23. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 23 Noble Gases Group 18 or 8A or VIII A Single atom (monoatomic) gases Little reactivity

24. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 Metals, Nonmetals & Mettaloids

25. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 25 Metals Shiny/ metallic luster Good conductor of heat & electricity Malleability Ductile Tend to lose electrons

26. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 26 Non-Metals Brittle solids Many gases at room temperature Liquid – bromine Poor conductors Tend to gain electrons Often share electrons with other non- metals to form covalent bonds

27. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 27 Mettalloids Some characteristics of metals and some characteristics of non-metals. All are solids at room temperature Semi-conductors of electricity. B, Si, Ge, As, Sb, Te, At

28. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 28 Transition Metals

29. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 29 Figure 2.21 The Periodic Table

30. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 30 THE END!!!!!!!!!!