Lecture #4 - Chemistry 2A-c w2009(Ch2-13 Group 1A Alkali...

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Group 1A – Alkali metals (Li, Na, K, etc.) Group 2A – Alkaline Earth metals (Be, Mg, Ca, etc.) Group 7A – Halogen (F, Cl, Br, I, etc.) Group 8A – Inert (noble or rare) gases (He, Ne, Ar, Kr, Xe, etc.) Important observation : Inert gases He, Ne, Ar, Kr, and Xe have 2, 10, 18, 36, and 54 electrons are extra-stable. Properties and bonding of atoms depends on the electron arrangement or electron configurations Chemistry 2A Chemistry 2A -c w2009 c w2009 (Ch2 (Ch2 -13) 13) The alkali metals tend to form cations with a +1 charge and the halogens tend to form anion with a –1 charge in chemical reactions. Example : 2Na(s) + Cl 2 (g) 2NaCl(s) [=(Na + )(Cl - )] Half –reactions: Na Na + + e- Cl + e- Cl - Ionic bond Exist as Li + , Na + , K + in compounds Exist as Be 2+ , Mg 2+ , Ca 2+ in compounds Exist as F - , Cl - , Br - in compounds Na (11 p’s + 11 e - ‘s) Na + (11 p’s + 10 e - ‘s) Mg (12 p’s + 12 e - ‘s) Mg ++ (11 p’s + 10 e - ‘s) O (8 p’s + 8 e - ‘s) O 2- (8 p’s + 10 e - ‘s) Cl (17 p’s + 17 e - ‘s) Cl - (17 p’s + 18 e - ‘s) Ionic Compounds: MgCl 2 = (Mg ++ )(2Cl - ) MgO = (Mg ++ )(O 2- ) Same # of electrons as in Ne Same # of electrons as in Ar
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Naturally occurring C and O Chemistry 2A Chemistry 2A -c w2009 c w2009 (Ch2 (Ch2 -14) 14) A mole of substance contains the Avogadro’s number of elementary entities The # of 12 C atoms in exactly 12 g of
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This note was uploaded on 02/25/2009 for the course CHEM chem 2a taught by Professor Ng during the Winter '09 term at UC Davis.

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Lecture #4 - Chemistry 2A-c w2009(Ch2-13 Group 1A Alkali...

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