1. Atoms and the Periodic Table Chapter 8

2. Homework Assignment Chap 8 Read p 203 – 211; 216 - 222 Applying the Concepts (p 222): 1 – 13, 15 – 17, 19, 23 - 35, 39 – 43, 45 - 49

3. Dalton’s Atomic Theory (1808) (Listed on p 203) 1.Elements are composed of extremely small particles called atoms. 2.All atoms of a given element are identical, having the same size, mass and chemical properties. 3.The atoms of one element are different from the atoms of all other elements. 4. Compounds are composed of atoms of more than one element. The relative number of atoms of each element in a given compound is always the same. 5. Chemical reactions only involve the rearrangement of atoms. Atoms are not created or destroyed in chemical reactions.

4. Particles in an atom

5. Cathode Ray Tube N S J.J. Thomson, discovered the electron (1906 Nobel Prize in Physics) Fig 8.2

6. 1.Atom’s positive charge is concentrated in the nucleus 2.Proton (p) has opposite (+) charge of electron (-) (1908 Nobel Prize in Chemistry) Fig 8.5Fig 8.6

7. atomic radius ~ 1 x 10 -10 m nuclear radius ~ 5 x 10 -15 m Planetary Model of the Atom “If the atom is the Houston Astrodome, then the nucleus is a marble on the 50-yard line.” Empty space!

8. 6 protons, 8 (14 - 6) neutrons, 6 electrons 38 protons, 46 (84 - 38) neutrons, 38 electrons Do You Understand Isotopes? How many protons, neutrons, and electrons are in C 14 6 ? How many protons, neutrons, and electrons are in Sr 84 38 ?

9. Visible light consists of electromagnetic waves Electromagnetic radiation: emission and transmission of energy in the form of electromagnetic waves. Speed of light (c) in vacuum = 3.00 x 10 8 m/s Fig. 7.2

10. Fig. 7.3 The Electromagnetic Spectrum

11. White light is separated into its color components by a prism

12. White light is separated into its color components by a diffraction grating The tracks of a compact disc act as a diffraction grating, producing a separation of the colors of white light.

13. Line Emission Spectrum of Hydrogen Atoms Fig 8.8 Atomic Emission Spectra

14. 7.3

15. First recorded emission spectrum of the sun (1817) intensity wavelength

16. 1.e - can only have specific (quantized) energy values 2.light is emitted as e - moves from one energy level to a lower energy level Bohr’s Model of the Atom (1913) n (principal quantum number) = 1,2,3,… Fig 8.10 e-

17. E = h Low energyHigh energy E green > E red Fig 9.18

18. Electron configurations of some atoms Valence electrons ≡ electrons in outermost shell

19. Fig 8.17 Periodic Table of the Elements

20. Periodic Properties of the Elements © 2009, Prentice-Hall, Inc. Development of Periodic Table Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.

21. Metals good conductors of heat and electricity shiny, ductile, malleable all solids with one exception Physical Properties of the Elements

22. Nonmetals poor conductors dull appearance, brittle consist of solids, liquids, and gases Physical Properties of the Elements

23. Metalloids Have some characteristics of metals and some of nonmetals For instance, silicon looks shiny, but is brittle and fairly poor conductor Physical Properties of the Elements

24. Period Group Alkali Metal Noble Gas Halogen Alkali Earth Metal Fig 8.17 Periodic Table of the Elements

25. Periodic Properties of the Elements Alkali Metals – Group 1A Alkali metals are soft solids Never found free in nature All react violently with water:

26.  Soft solids but harder than alkali metals  Never found free in nature  All react slowly with water to form bases:

27. Periodic Properties of the Elements T HE H ALOGENS – G ROUP 7A Typical nonmetals The name comes from the Greek words meaning “salt formers” iodine chlorine bomine

28. All very unreactive Exist as atoms

29. Fig 8.18 Show only valence electrons! Electron dot notation for the representative elements

30. Chemistry In Action Natural abundance of elements in Earth’s crust Natural abundance of elements in human body