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Chapter Three

Chapter Three

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Chapter Three

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  1. 0 Chapter Three Atoms and the Periodic Table

  2. 0 Atomic Theory • All matter is composed of atoms • Atoms of each element are unique • Atoms are composed of subatomic particles (protons, neutrons and electrons) • Atoms combine to form compounds in definite proportions • Chemical compounds undergo changes in composition and identity in reactions, atoms remain unchanged • Atoms change identities in nuclear reactions

  3. 0 Nature of the Atom • Atoms are small 10-11 meters • 1 Angstrom = 10-10 meters

  4. 0 Subatomic Particles

  5. 0 Atomic Number (Z) • number of protons in nucleus • unique for each element • elements placed in periodic table by increasing number of protons sodium has 11 protons 11Na carbon has 6 protons 6C

  6. 0 Elements are neutral Number of positive protons = Number of negative electrons

  7. 0 Mass Number (A) Number of particles in the nucleus Protons + Neutrons = Mass Number Protons + Neutrons = Nucleons

  8. 0 Isotopes • Elements may have several different isotopes • Same number of protons, different number of neutrons

  9. 0 Atomic Weight The average mass number of all the naturally occurring isotopes according to relative abundance. Lithium is 6.941. There is more lithium-7 than lithium-6

  10. 0 Electrons in Atoms • Energy is quantized vs continuous • Quantize = step function • Continuous = all values are present • Similar to digital vs analog

  11. 0 Shells, Subshells and Orbitals • Shells • n = principle quantum number • Same as period on periodic table • Subshells • In each shell s > p > d > f • Orbitals • 2 electrons per orbital

  12. 0 Orbitals • s subshell – 1 orbital – 2 electrons • p subshell – 3 orbitals – 6 electrons • d subshell – 5 orbitals – 10 electrons • f subshell – 7 orbitals – 14 electrons

  13. 0 Number of Electrons in Shells 2n2 n is the number of the row in the periodic table

  14. 0 Aufbau – order of filling • 1s2 • 2s22p6 • 3s23p63d10 • 4s24p64d104f14 • 5s25p65d105f14(5g18) • 6s26p66d106f14(6g18)(6h22) • 7s27p67d106f14(6g18)(6h22)(7i26)

  15. 0 Increasing Energy • 1s22s22p63s23p64s23d104p6 • Carbon 6 electrons • 1s22s22p2 • Sodium 11 electrons • 1s22s22p63s1

  16. 0 • Aluminum – 13 electrons • 1s22s22p63s23p1 • Calcium – 20 electrons • 1s22s22p63s23p64s2 • Iron – 26 electrons • 1s22s22p63s23p64s23d6 • Bromine – 35 electrons • 1s22s22p63s23p64s23d104p5

  17. 0 Using the Periodic Table • Lithium – 3 electrons • 1s22s1 • Sodium – 11 electrons • 1s22s22p63s1 • Potassium – 19 electrons • 1s22s22p63s23p64s1 • All end in “ns1” configuration

  18. Fluorine – 9 electrons • 1s22s22p5 • Chlorine – 17 electrons • 1s22s22p63s23p5 • Iodine – 53 electrons • 1s22s22p63s23p64s23d104p65s24d105p5 • All end in “ns2np5” configuration

  19. The Periodic Table • Classification by Properties • Arranged by increasing atomic number • Rows=periods, columns=groups (families) • Main Group – Representative • IA, IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA • Transition Metals • 10 columns in middle of table • Inner-transition Metals • 14 columns at bottom of table

  20. Elements in same column have similar properties • Cu, Ag and Au – shiny metals, malleable, conduct electricity

  21. Names of Families • Alkali Metals (IA) Na and K • Alkaline Earth Metals (IIA) Mg and Ca • Halogens (VIIA) F, Cl, Br and I • Noble Gases (Inert Gases) (VIIIA) He, Ne, Ar, Kr and Xe

  22. Neighboring Groups • Metals • Non-metals • Metalloids (Semiconductors)

  23. Dot Structures for Atoms • Valence electrons for representative elements = group number • Octet rule

  24. Noble Gas Shorthand • [He] = 1s2 Li = 1s22s1 or [He]2s1 • [Ne] = 1s22s22p6 Na = [Ne]3s1 Mg = [Ne]3s2 • [Xe] = 1s22s22p63s23p64s23d104p65s24d105p6 Ba = [Xe]6s2

  25. Location on Periodic Table shows location of last electron in configuration • Cs = 6s1 • Sr = 5s2