Bonding

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  • BONDING
    • Ionic bonding
      • Atoms are formed when e- are transferred from one atom to another
      • Electrostatic attraction holds +ve and -ve ions together = VERY STRONG
      • Ionic compounds form a giant ionic lattice
      • Properties
        • Conduct elec' when MOLTEN or DISSOLVED but not when solid... because ions not free to move so no charge present.
        • HIGH MELTING POINT due to strong electrostatic forces which are require a lot of KE to overcome
        • Often dissolve in water due to the polarity of the water. -ve molecules are pulled away by water molecules causing it to dissolve
      • Egs NaCl MgCl2
    • Covalent bonding
      • Molecules are formed when two or more atoms are covalently bonded together
      • The covalent bond involved sharing e- so they have a full outer shell
        • Both +ve nuclei are attracted electro statically to shared e-
      • A dative covalent bond is where both e- come from the one atom eg NH4+
        • Represented by an arrow coming away from donor atom
      • Properties
        • LOW MELTING POINT as only have to overcome weak ID ID or H bonds, not the covalent bonds
        • DON'T CONDUCT ELEC' as there are no e- free to move to create a current
        • Insoluble in water, polar water molecules are more attracted to each other than molecular substance
      • Egs CO2 O2 N2
    • Giant covalent
      • HIGH MELTING POINT need to break many strong bonds which requires a lot of KE
      • Insoluble in Water
      • Won't conduct electricity apart from graphite- as graphite has delocalised e- and so can carry current
      • Egs SiO2, Diamond
    • Metallic bonding
      • HIGH MELTING POINT due to strong metallic bonds - the more delocalised e- affects the mp as this means stronger bonds
      • Insoluble as the strength of metallic bonds is too strong to overcome
      • Will conduct elec' as the delocalised e- can carry charge
      • Made of positive metal cations and sea of delocalised e- which are attracted to each other
      • Egs Mg Na Al

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