Chemistry – Jan 4, 2018 P3 Challenge – Today’s Objective – Find New Seat Midyear Test (first semester post – 4 questions, second semester pre- 6 questions) Counts only for a P3 grade. Answer 1,2,3 and 6. IDK is ok for the others. Today’s Objective – Polyatomic Ions
Chemistry – Jan 4, 2018 Objective – Polyatomic Ions Assignment: Polyatomic Ions Memory Assignment Quiz on Thursday 1/11 Agenda Midyear Test Ions Review Polyatomic ions Memory strategies Patterns, games, apps, flashcards
Ions In neutral atoms, # protons = # electrons Identity of an atom is solely dependent on # protons, Z # electrons can and often do vary some due to chemical reactivity, though usually not more than by +/- 3 If #electrons ≠ #protons, then an ion is formed. Anions have a negative charge and have extra electrons Ex: F + e- F- O + 2 e- O-2 Cations have a positive charge and are missing electrons Ex: Na Na+ + e- Ca Ca+2 + 2 e-
Ions and the periodic table Group of Elements Type of ion formed Alkali Metals & Hydrogen + Alkaline Earth Metals +2 Group 13 +3 Group 15 –3 Group 16 –2 Halogens – Group of Elements Type of ion formed Noble Gases None Transition Metals Multiple positive ions Lanthanides and Actinides Uncommon, varies Other elements with only one possible charge: Ag+, Zn2+, Cd2+, Al3+, Ga3+ (memorize)
Polyatomic Ions and compounds Often two or more atoms form a group that has a collective charge. Memorize the polyatomic ions (see next slide). Make flash cards. Seriously. NEVER change the formula of a polyatomic ion Imagine a shrink-wrap packaging goes around the number and types of atoms and you cannot break up this bundle
Exit Slip - Homework Exit Slip: What’s Due? (Pending assignments to complete.) Polyatomic Ions Memory Assignment (Quiz on Thursday 1/11) What’s Next? (How to prepare for the next day) Read p159-175 about ions and Ionic bonding