Structure and bonding

Structure and bonding

1. Compounds are substances in which atoms of two or more elements are chemically bonded

2. Bonding

   • Ionic
     • Atoms gain or lose electrons and become ions
       • Atoms that lose electrons become positively charged
       • Atoms that gain electrons become negatively charged
       • Ions have a structure of a noble gas (complete outer shell)
   • Covalent
     • Atoms share electrons in their outer shells.
     • When atoms share pairs of electrons. These bonds between atoms are strong.
     • Simple covalently bonded substances are H2, Cl2, O2, HCl, H2O, NH3 and CH4
     • Others have giant covalent structures (macromolecules), such as diamond and silicon dioxide

3. Elements

   • Group 1
     • Alkali Metals
     • All react with non-metals to form ionic compounds in which the metal has one positive charge
   • Group 7
     • Halogens
     • All react with alkali metals to form ionic compounds where the halide ions have a single negative charge

4. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.