1. Covalent Bonding
Last Bits

2. Coordinate Covalent Bond
bond formed when:
2 atoms share pair electrons but
both electrons donated by same atom
many polyatomics have coordinate covalent bonds
must be able to recognize them

3. H .. + H : N : H H+1 .. Ammonium, NH4+1 Oh oh – no electrons at all!
2 electrons just hanging around

4. Ammonium, NH4+1 +1 H ..
H : N : H .. H
Both electrons in this bond were donated by the N atom

5. .. + H : O : H H+1 .. Hydronium, H3O+ 2 pairs of nonbonding electrons
zero electrons

6. Hydronium, H3O+ +1 H
Both electrons are provided by the oxygen atom ..
H : O : H ..

7. NETWORK SOLIDS: Carbon
Most covalent substances are molecular
Carbon can form 4 bonds with 4 other C atoms
Allows C to build up extensive network, like a crystal lattice
Ex: diamond
Hard, nonconductors (except graphite)
high mp & bp, high Hf and Hv
Strong covalent bonds hold atoms together

8. Diamond Structure

9. Network solids: Silicon
Silicon can also form network solids
Ex: quartz or SiO2
Quartz has very complicated crystal structure