metalnonmetal ionic bond: metal + nonmetal metals: lose valence electrons –form cation –form...

Ionic Bond: MetalMetal + NonmetalNonmetal

• Metals: lose valence electrons – formform cation cation (+ ion)

• Nonmetals: gain electrons –form anionanion (- ion)

IONIC BONDING

• Involves Involves transfer of electronstransfer of electrons– electrons go from metal to nonmetalelectrons go from metal to nonmetal

• # electrons# electrons Lost Lost by by CationCation (metal) (metal)

= =

# electrons # electrons GainedGained by by Anion (nonmetal)Anion (nonmetal)

Metals are losers!Metals are losers!

• Na has configuration 2-8-1

• Na loses 1 electron → Na+1 –Na+1 configuration is 2-8 (Ne)

• What can taketake the valence electron from Na??

Na metal Na metal

Nonmetals are winners!Nonmetals are winners!

• Cl has configuration 2-8-7

• Cl gains 1 electron → Cl-1

– Cl-1 configuration 2-8-8 (Ar)

• What can donatedonate an electron to Cl ??

ClCl22 (g) (g)

Electron is transferred from Na to ClElectron is transferred from Na to Cl

Structure of Ionic Compounds

• Ions are attracted to each other by strong electrostatic interactions (between +/- ions)

• Ions form crystal lattice – regular 3-D pattern or array – Ions are held in fixed positions (solid state)

lattice structure lattice structure

NaCl has its own NaCl has its own unique propertiesunique properties

The more Na and ClThe more Na and Cl22, the , the larger the resulting NaCl larger the resulting NaCl crystal crystal

-just keep adding on to it-just keep adding on to it

Different Different representations of representations of a crystal latticea crystal lattice

Lewis Diagrams for Ionic Compounds

NaCl's Lewis structure:NaCl's Lewis structure:

[[NaNa]]+1 +1 [ [ Cl Cl ]]-1-1••••

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Remember: Lewis diagrams show valence electrons!Remember: Lewis diagrams show valence electrons!

Predicting Ionic Compounds

• What is ionic compound formed from What is ionic compound formed from calcium and iodine?calcium and iodine?

• Calcium - metal - 2 valence electrons Calcium - metal - 2 valence electrons - loses both electrons - loses both electrons [[CaCa]]+2+2

• Iodine - nonmetal - 7 valence electrons Iodine - nonmetal - 7 valence electrons - gains 1 electron - gains 1 electron [[ I I ]]-1-1

How many iodine ions do you need to make a How many iodine ions do you need to make a neutral compound?neutral compound? 22

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Lewis Diagram of Calcium iodide

Ca 2-8-8-2 → CaCa 2-8-8-2 → Ca+2+2 2-8-8 2-8-8I 2-8-18-18-7 → II 2-8-18-18-7 → I-1-1 2-8-18-18-8 2-8-18-18-8

[[CaCa]]+2+2[:[:II:]:]-1-1[:[:II:]:]-1-1 or [: or [:II:]:]-1-1[[CaCa]]+2+2[:[:II:]:]-1-1

Note: total charge adds up to zero Note: total charge adds up to zero

- compounds are neutral- compounds are neutral

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