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Important reminders for upcoming assignments and quizzes in a college-level chemistry course. Topics include polyatomic ions, polar and nonpolar molecules, and their respective shapes. Students are encouraged to review these concepts before the respective deadlines.
Typology: Study Guides, Projects, Research
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Topic reservation due before class today - reserve one ASAP if you have not yet.
Phase 2: 6-8 paragraph essay - instructions are posted in D2L. Due before class Monday, Apr 27.
Discussion assignment 2: Lecture quiz 3 will be available in D2L before noon Tuesday. It will be due before class next Monday, Apr 20. Lec 9 post and Lec 10 pre assignments will be in MC Tuesday before noon - due before class next Mon, Apr 20 Announcements Monday, April 13, 2009
Polyatomic ion: charged molecule NH 4
(ammonium ion): tot # ve
? full octets/duets? Polyatomic ions do not follow the rules for the normal number of covalent bonds to atoms (this is one reason they are charged!) NO 3
Lewis structures of polyatomic ions
HCl is a polar molecule because it can be separated into δ+ and δ- sides: Net dipole moment: one dipole arrow that represents the polarity of the entire molecule. It points from the δ+ side to the δ- side. cannot be separated into δ+ and δ- halves may have polar bonds that completely cancel each other
has no net dipole moment A nonpolar molecule: Is CH 3 Cl polar or nonpolar? Is CO 2 polar or nonpolar? (draw it with the correct shape) Polarity of molecules
Linear shape: 2 atoms attached to the central atom, no lone pairs on the central atom Bent shape: 2 atoms attached to the central atom, lone pairs on the central atom Trigonal planar shape: 3 atoms on central atom, no lone pairs on central atom Trigonal pyramidal shape: 3 atoms on central atom, lone pairs on central atom Tetrahedral shape: 4 atoms attached to central atom Shapes of molecules
Linear Bent Trigonal planar Trigonal pyramidal Tetrahedral If all bonds have equal polarity: If bonds have unequal polarities: Shapes and polarity