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The Atom

The Atom. C = Carbon N = Nitrogen O = Oxygen Cl = Chlorine Ba = Barium. U = ? Cf = ? Bk = ? Md = ? Es = ?. Elements and Symbols. K = Pb = W = Sb =. Co = Cu = Cr = Mg = Mn =. Atom : basic unit of matter

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The Atom

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  1. The Atom

  2. C = Carbon N = Nitrogen O = Oxygen Cl = Chlorine Ba = Barium U = ? Cf = ? Bk = ? Md = ? Es = ? Elements and Symbols

  3. K = Pb = W = Sb = Co = Cu = Cr = Mg = Mn =

  4. Atom: basic unit of matter • Smallest unit of matter that individually retains the chemical characteristics of an element • Consists of a dense central region, called a nucleus, surrounded by a negatively charged cloud • Contains three types of subatomic particles: • Proton • Neutron • Electron

  5. The Proton • Charge = + 1.602×10−19  C • Called “+1” for clarity • Located in nucleus of atom • Mass = 1.672 x 10–24 g • Approx. 1 unified atomic mass unit (u) • 1 u = 1.66 x 10–24 g • 1/12 the weight of a Carbon-12 atom

  6. The Neutron • No charge (0 C) • Located in nucleus • Mass = 1.675 x 10–24 g • Approx. = 1 u

  7. The Electron • Charge = –1.602 x 10–19 C • Called “–1” • Located outside nucleus in an e- “cloud” • Mass = 9.109 x 10-28g • Approx. = 0 u

  8. Plum Pudding Model • J.J. Thomson • 1904

  9. Gold Foil Experiment • Ernest Rutherford • 1909 • Proved J.J. Thomson’s theory wrong • Evidence for existence of protons

  10. Evidence of Electrons

  11. Dmitri Mendeleev (1834-1907) • Russian chemist • Arranged elements in horizontal rows in order of increasing atomic weight • Started new rows in order to make columns of chemicals with similar characteristics • Left spaces open for elements yet to be discovered

  12. Classification of the Periodic Table Classification by Physical Properties

  13. Metals • Shiny • Conduct electricity • Ductile • Can be drawn through wires • Malleable (Shapeable) • High M.P. & B.P • Solids @ room temp • Except Hg

  14. Non-Metals • Don’t tend to conduct well • Not usually ductile • Tend to be brittle • Low M.P. & B.P. • Many are gases at r.t.

  15. Metalloids • Have chemical characteristics in between those of metals and non-metals • Includes elements: B (Boron), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Polonium (Po), Astatine (At)

  16. Classification by Electronic Properties

  17. Alkali Metals • Group 1 (1A) • Li, Na, K etc. • Soft, shiny metals • Conduct heat and electricity • React violently with H2O • Form H2(g) and alkaline (basic) solutions

  18. Akali(ne) Earth Metals • Group 2 (2A) • Be, Mg, Ca etc. • Not as reactive as Alkali Metals, but still quite reactive • Tend to make basic solutions when placed in water

  19. Transition Metals • Groups 3-12 • Tend to have high densities and B.P. • All are metals • Often used for electrical conduction • Often have vivid colors when in solution • Used for pigments

  20. Colors of Transition Metal Compounds Nickel Cobalt Copper Zinc Iron

  21. Lanthanides • Elements 57-71 • Lanthanum (La) to Lutetium (Lu) • Commonly used in lasers • Can deflect UV and infrared rays

  22. Actinides/Actinoids • Elements 89-103 • Actinium (Ac) to Lawrencium (Lr) • Only Actinium, Thorium (Th), and Uranium (U) occur naturally • Others created by neutron bombardment • Radioactive

  23. Groups 13(3A) – 16(6A) • No common name • Boundary between metals and non-metals occurs here • Contain elements abundant in earth’s crust, atmosphere, and living things • Contains the metalloids

  24. Halogens • Group 17 (7A) • Love to form salts with metals • NaCl, KBr, CaCl2 • Like to form diatomic molecules • F2, Cl2, Br2

  25. Noble Gases • Group 18 (8A) • Very unreactive • Don’t like to bond to other molecules • Generally not abundant

  26. Diatomic Molecules Dinitrogen (N2) • Molecules consisting of only two atoms of either the same or different elements • O2 • CO • Homonuclear Diatomic Molecule: a molecule made of two atoms of the same element • H2 • Heteronuclear Diatomic Molecule: a molecule made of two atoms that are different elements • NO

  27. Allotropism • The existence of multiple pure forms of an element, in the same phase (solid, liquid, or gas), that differ in structure • Different forms are called allotropes • Can exhibit varied physical properties and chemical behaviors • Don’t confuse allotropes with isotopes!!! O2 O3

  28. Which atom does the picture below represent?

  29. Atomic # • # of protons Atomic symbol Atomic Mass Atomic Weight Mass # Molar Mass

  30. Identify the atomic mass, number of protons, and number of neutrons for the following elements.

  31. Isotopes • Atoms of the same element that have different atomic masses • Same number of protons • Different # of neutrons

  32. Problems • Lithium has two natural isotopes, 6Li and 7Li, which have percent abundances of 7.5% and 92.5% respectively. What is the average atomic mass of Lithium? • Using the percent abundances below, calculate the average atomic mass for Carbon • C-12 = 98.890% • C-13 = 1.110% • C-14 = 0.0000000001% • Antimony (Sb) has two stable isotopes, 121Sb and 123Sb with masses of 120.9038 u and 122.9042 u, respectively. Calculate the percent abundances of these two isotopes

  33. Atomic Orbitals and Electron Configurations

  34. Atomic Orbitals • Orbital: a specific region in an atom thought to posses the highest probability of containing the electron in question at any one time • Only hold maximum of two electrons at a time • 4 basic types: s, p, d, f

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