1. Atoms and the Periodic Table Chapter 8

2. Homework Assignment Chap 8 Read p 223 – 231; 236 - 242 Applying the Concepts (p 243): 1 – 13, 15 – 17, 19, 23 - 35, 39 – 44, 46 - 50

3. Dalton’s Atomic Theory (1808) (Listed on p 224) 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. Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes - atoms of the same element (X) with different numbers of neutrons in their nuclei X A Z H 1 1 H (D) 2 1 H (T) 3 1 U 235 92 U 238 92 Mass Number Atomic Number Element Symbol 0.72% natural abundance

9. 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 ?

10. 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

11. Fig. 7.3 The Electromagnetic Spectrum

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

13. 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.

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

15. 7.3

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

17. 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-

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

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

20. Fig 2.9

21. Metals good conductors of heat and electricity shiny, ductile, malleable all solids with one exception Nonmetals poor conductors dull appearance, brittle consist of solids, liquids, and gases Physical Properties of the Elements

22. Period Group Alkali Metal Noble Gas Halogen Alkali Earth Metal p 237

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