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Announcement

Announcement. Homework is due at the beginning of class. Put it on your desk during the first two minutes. HW detentions emailed at the beginning of class.

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Announcement

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  1. Announcement • Homework is due at the beginning of class. • Put it on your desk during the first two minutes. • HW detentions emailed at the beginning of class. • You will need a “homework detention rescinding form” signed (after class!) if you didn’t complete your HW by the first two minutes of class.

  2. Review Review subatomic particles, mass number, atomic number, average atomic mass

  3. The Periodic Tableof the Elements

  4. Dmitri Mendeleev (1869) • Organized the elements by atomic mass and other properties • Looked for repeating patterns • When arranged by increasing atomic mass, similarities in chemical properties appeared at regular intervals. • Periodic: things that repeat at regular intervals

  5. The Periodic Table is Born • Mendeleev then created a table where elements with similar properties were grouped together: the first periodic table of the elements (1869)

  6. The First Periodic Table

  7. Atomic mass • Always increasing? • Empty spaces • Predicted they would be filled by elements with certain properties • By 1886 these spaces were filled, by elements with those properties!

  8. Another Contribution • Henry Moseley arranged elements by their atomic number, not by atomic mass • Periodic Law: the physical and chemical properties of the elements are periodic functions of their atomic numbers • Periodic functions: repeating patterns • Related to the number and location of electrons

  9. Increasing Atomic Number (and, more or less, atomic mass)

  10. Periods (across rows) Groups (down columns)

  11. Group Numbers 1 18 2 13 14 15 16 17

  12. Elements in the same group have similar chemical and physical properties.

  13. Areas of the PTE Non-metals Metals

  14. A quick tour of the periodic table

  15. Metals Solid at room temperature Conduct electricity Shiny Ductile and malleable: can be made into wires and beaten into sheets

  16. Group 1: Alkali Metals • Extremely reactive • Why? • Don’t exist alone naturally

  17. sodium potassium cesium (l) rubidium

  18. http://video.google.com/videoplay?docid=-2134266654801392897&ei=59rqSt_wCNSclAfixvCdCQ&q=alkali+metals&hl=en#http://video.google.com/videoplay?docid=-2134266654801392897&ei=59rqSt_wCNSclAfixvCdCQ&q=alkali+metals&hl=en#

  19. Group 2: Alkaline Earth Metals Very reactive

  20. Non-Metals Liquids or gases at room temperature Don’t conduct electricity

  21. Group 17: Halogens • Very reactive non-metals • Need only one electron to fill valence shell • All exist as diatomic molecules • Cl2, Br2, I2 (all colored)

  22. Halogens – colored diatomic molecules

  23. Group 18: Noble Gases Not reactive Gases at room temperature Stable electron arrangement

  24. The Giant Periodic Table Project 6 C 12.01

  25. The Giant Periodic Table Project Be neat Be bold! We need to be able to read this from anywhere in the room! Be creative, but not cluttered. Be accurate. Atomic mass to TWO digits (Ex: 12.01) is ideal.

  26. Electron Configuration • The arrangement of electrons in an atom • Each element’s atoms are different • How do we figure out what the electron configuration looks like?

  27. So where are the electrons? Electrons do NOT orbit like planets.

  28. Energy Levels • Major shells (layers) around the nucleus • lower levels filled before higher levels are filled • 1st: 2 electrons • 2nd: 8 electrons • 3rd: 8 electrons

  29. Practice with Simple Electronic Structure • H • He • B • Mg • Li • Be • O • Ne • Cl

  30. Electron Apartment Building

  31. Electronic Structure Energy levels Sub-levels Orbital Two electrons per orbital

  32. Inside energy levels… Each energy level has one or more sub-level made from different shaped orbitals.

  33. Sub-levels are made up of one or more orbitals

  34. What is an orbital? Orbital: An area where you expect to find the electron.

  35. Sub-levels • Different shapes • s – sphere • one orbital • p – figure eight • three orbitals • d – • five orbitals • f – • seven orbitals

  36. p Sub-level • p sub-level has three orbitals • px, py, pz

  37. How do we figure out where the electrons are? • 1. Figure out the energy levels of the orbitals • 2. Add electrons to the orbitals according to three rules • Three Rules for Electron Configuration

  38. An electron goes to the lowest-energy orbital that can take it. 1: Aufbau Principle

  39. No two electrons can have exactly the same configuration description Can have the same orbital, but must have opposite spins. 2: Pauli Exclusion Principle

  40. Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron All electrons that are by themselves in an orbit must have the same spin. 3. Hund’s Rule

  41. Energies of sub-levels

  42. Multiple choice practice

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