1. AS Chemistry
Coordinate or
Dative Covalent
Bonding
NH4+
Al2Cl6 CO
H3O+

2. Draw a dot and cross diagram to show how NH3 bonds to H+ to form NH4+

3. Ammonium ion : NH4+ . H N + H+ H + N H NH3 + H+  NH4+
What is unusual about the covalent bond that is formed?

4. Co-ordinate (Dative Covalent) Bonding
= a covalent bond formed when both shared electrons are provided by only one atom.
The shared e- pair comes from a lone pair on the donor atom
eg N of NH3, O of H2O
The atom accepting the lone pair must have an incomplete outer energy level
eg H+, Al in AlCl3, C in CO

5. (only the method of formation differs).
Dative are physically and chemically identical to ordinary covalent bonds
(only the method of formation differs).
Represent by X: Y instead of X Y

6. Draw a dot and cross diagram to show the bonding in H3O+

7. Hydronium ion : H3O+ . . . H O + H+  . . H O +
Why is H4O2+ unlikely to form from H3O+?

8. H4O2+ is unlikely to form via the second lone pair because;
the second H+ is repelled by H3O+

9. Draw a dot and cross diagram to show the bonding in the dimer Al2Cl6

10. Aluminium chloride dimer, Al2Cl6. Cl Al
Al2Cl6

11. Draw a dot and cross diagram to show the bonding in carbon monoxide CO

12. C O N Carbon monoxide, CO Isoelectronic with N2 :
What does isoelectronic mean?

13. Why does NH3 react readily with BF3 to form a stable compound?

14. . N B H F N of NH3 has a lone pair on the N atom.
The B atom of BF3 has an incomplete energy level
and can form a dative bond with the N atom. . H N F B
ALL atoms now have a noble gas configuration 14

15. The End