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

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

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

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

(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

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

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

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

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

Aluminium chloride dimer, Al2Cl6 . Cl Al Al2Cl6

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

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

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

. 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

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