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Chapter 4 Part 1 - Ionic Compounds
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Electron Review l Valence electrons - electrons in the outer energy level. l Core electrons -those in the energy levels below.
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Electron Review Which type of electron is responsible for bonding? Why?
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Electron/Periodic Table Review l Atoms in the same column: –Have the same outer electron configuration. –Have the same valence electrons. –Easily found by looking up the group number on the periodic table.
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Electron/Periodic Table Review Group 2A How many Valence Electrons? Group 8A How many Valence Electrons?
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Noble Gas Configuration Q: What’s so special about 8 electrons? A: STABILITY!
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Noble Gas Configuration All atoms seek to achieve the same stability of a noble gas by gaining, losing, or sharing electrons with another atom. HOW?
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Noble Gas Configuration THROUGH BONDING! Ionic bonding Covalent bonding
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Review Question Group 1A and 2A are what type of element? (metal, nonmetal, metalloid)
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Metals l Metals lose electrons to attain noble gas configuration. l They make positive ions called cations.
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Electron Dots For Cations Metals will have few valence electrons Ca
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Electron Dots For Cations l Metals will have few valence electrons l These will come off Ca
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Electron Dots For Cations l Metals will have few valence electrons l These will lose electrons l Form positive ions Ca 2+
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Review Question Group 5A elements are mostly what type of element? (metal, nonmetal, metalloid)
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Nonmetals l Nonmetals gain electrons to attain noble gas configuration. l They make negative ions called anions
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Electron Dots For Anions l Nonmetals will have many valence electrons. l They will gain electrons to fill outer shell. P P 3-
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Noble Gas Configurations l All atoms react to achieve noble gas configuration. l Noble gases have 8 valence electrons l Also called the octet rule. Ar
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Ionic Bonding l Anions and cations are held together by opposite charges. l These are called ionic compounds l Ionic compounds are also called salts.
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Ionic Bonding l The bond is formed through the transfer of electrons. l Electrons are transferred to achieve noble gas configuration by both metal and nonmetal.
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Ionic Bonding NaCl
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Ionic Bonding Na + Cl -
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Ionic Bonding l All the electrons must be accounted for! CaP
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Ionic Bonding CaP
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Ionic Bonding Ca +2 P
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Ionic Bonding Ca +2 P Ca
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Ionic Bonding Ca +2 P -3 Ca
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Ionic Bonding Ca +2 P -3 Ca P
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Ionic Bonding Ca +2 P -3 Ca +2 P
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Ionic Bonding Ca +2 P -3 Ca +2 P Ca
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Ionic Bonding Ca +2 P -3 Ca +2 P Ca
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Ionic Bonding Ca +2 P -3 Ca +2 P -3 Ca +2
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Ionic Bonding Ca 3 P 2 Ionic Compound
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Properties of Ionic Compounds l Crystalline structure. l A regular repeating arrangement of ions in the solid. l Ions are strongly bonded. l Structure is rigid. l High melting points- because of strong forces between ions.
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Crystalline structure
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Do they Conduct? l Conducting electricity is allowing charges to move. l In a solid, the ions are locked in place. l Ionic solids are insulators. l When melted, the ions can move around. l Melted ionic compounds conduct. l Have to get them to 800ºC. l Dissolved in water they conduct – electrons are free to move.
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Ionic solids are brittle +-+- + - +- +-+- + - +-
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+ - + - + - +- +-+- + - +- l Strong Repulsion breaks crystal apart.
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Metallic Bonds l How atoms are held together in a metal solid. l Metals hold onto there valence electrons very weakly. l Think of them as positive ions floating in a sea of electrons. l Electrons are free to move from atom to atom. l Electrons moving = electricity!!!
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Sea of Electrons ++++ ++++ ++++ l Electrons are free to move through the solid. l Metals conduct electricity.
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Metals are: l Malleable - Hammered into shape (bend). l Ductile - drawn into wires.
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Malleable ++++ ++++ ++++
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++++ ++++ ++++ l Electrons allow atoms to slide by.
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