C2.1 Structures and Bonding

C2.1 Structures and Bonding

1. Chemical Bonding

   • Atoms of 2 or more elements react = compound
   • Noble Gas (group 0) stable and unreactive
   • Sharing electrons = covalent. Transferring electrons = ionic
   • Losing Electrons to form positive ions
     • In ionic bonding atoms lose or gain electrons forming charged particles (ions)
       • Ions have structure of a noble gas (2,8/2,8,8)
     • Ions have one more proton than electron making a positively charged ion.
   • Gaining Electrons to form negative ions
     • Non metals with metals: non metal gains electrons to obtain noble gas structure
     • More electrons than protons, negative charged ion
   • Both atoms aim for a stable structure

2. Ionic Bonding

   • Ions are held together by strong attracting forces between oppositely charged ions. This electrostatic force of attraction is called ionic bonding
   • Giant structure or lattice has forces from all directions holding it in place.
   • When bonding you must reach no charge

3. Formulae of ionic compounds

   • Group 1 metals = charge 1+. Group 2 metals = charge 2+. Group 7 non metals = charge 1-. Group 6 non metals = charge 2-
   • Names of transition metals compounds contain charge of ions in roman numerals in brackets. Eg. iron(lll) oxide = Fe3+ ions
   • Some ions are made of more than 1 element (CO3)
   • When things are in brackets you must multiply them out as they change the ratio

4. Covalent Bonding

   • When non metals react they share electrons forming molecules
   • Simple Molecules
     • They both need to gain electrons, so they share
   • Giant Covalent Structures
     • Macromolecules
     • Diamond
       • each carbon forms 4 covalent bonds

5. Metals

   • Metal Crystals
     • built up in layers like a regular pattern
     • Eg. Zinc crystals on the surface of steel
     • Steel can be dipped into molten zinc to prevent rust
   • Metallic Bonding
     • lattice of positively charged ions
     • Regular layers
     • Outer electrons can move through the structure - delocalised electrons
       • No longer linked with an ion
     • Strong electrostatic attraction between positive ions and negative electrons bind it