Topic: Chemical Bonding

chemical bond A chemical bond is a electrostatic force between atoms (caused by electrons attracting to the positive nucleus of another atom)

Why do atoms form bonds? To attain a noble gas configuration How do atoms form chemical bonds? By gaining, losing, or sharing electrons

A + B  AB When a bond formed = energy is released = reaction is exothermic

Breaking a Bond Absorbs Energy (endothermic)!

When a chemical bond is formed, PE is released, the bond becomes more stable You have to put energy in to brake a chemical bond, so PE increases and the overall system becomes less stable

Ionic Bonding Occurs between? (type of elements) Electrons (shared or transferred?) Metals and nonmetals Transferred, metal loses, nonmetal gains

electron transferred from Na to Cl

The more Na and Cl 2, the larger the resulting NaCl crystal -just keep adding on to it

Structure of Ionic Compounds Ions form crystal lattice – regular 3-D pattern or array – Ions held in fixed positions (solid state)

Ionic Bonding Type of structure? Properties Crystal Lattice High Boiling Point, High Melting Point, Hard, Brittle, Conduct electricity if melted or in solution (dissolved in water)

lattice structure  NaCl has its own unique properties

Metallic Bonding Occurs between? (type of elements) Electrons (shared or transferred?) Metals Mobile sea of electrons

Metallic Bonding Type of structure? Properties Crystal Lattice High Boiling Point, High Melting Point, Hard, Good Conductors electricity

Covalent Bonding Occurs between? (type of elements) Electrons (shared or transferred?) Nonmetals only shared

Covalent Bonding Type of structure? Properties Molecules – held together by IMF (intermolecular forces) Low Boiling Point, Low Melting Point, soft, poor conductors of electricity

Identify Bond Type from Formula ZnO N2O5N2O5N2O5N2O5Al CH 3 OH Al 2 O 3 CaBr 2 AuAg CO 2 Li 3 N Na 2 S Mg CsF H2OH2OH2OH2ONaCl SO 2 Cu CH 4 CovalentCovalent CovalentCovalent Covalent CovalentIonic Ionic Ionic IonicIonicIonic Ionic Metallic Metallic Metallic MetallicMetallic

So what? Why is structure so important? Structure determines physical properties!