L9 - Chemical Bonding (3) Flashcards
Define Dative Covalent Bond (Co-ordinate Bond).
A covalent bond in which one atom supplies both of the shared electrons in the bond.
What are co-ordinate bonds found in?
- Transition metal complex ions
- Ammonium ion (and other nitrogen-containing complexes)
- Hydroxonium ion
- Carbon monoxide
- Nitric acid
What is a donor?
The atom that supplies the shared pair of electrons.
What is an acceptor?
The atom with a vacant orbital that accepts the electron pair donated by the donor.
What must the atom acting as the donor have?
A lone pair of electrons.
Define Lone Pair.
A pair of electrons in the valence shell of the atom that are not involved in bonding.
Define Complex Ion.
Ions with a central metal ion bonded to one or more molecules / ions.
How does an ammonium ion form?
When ammonia reacts with H+.
How does a complex ion form?
When a transition metal ion dissolves in water.
Provide an example of a complex ion.
Al3+ bonded to 6 water molecules.
What makes transition metals, and elements in periods 1-3 available for bonding?
Transition metals and elements in periods 1-3 have valence electrons in d-orbitals that make them available for bonding.
What does the function of some biological molecules depend on?
Function of some biological molecules depends on binding a metal-ion containing cofactor.
State 8 biological molecules whose function depends on binding a metal-ion containing cofactor.
- Porphyrins
- Corrins
- Haemoglobin
- Myoglobin
- Cytochromes P450
- Vitamin B12
- Chlorophyll
- Photodynamic Therapy
What does the function of some drugs depend on?
Their ability to:
- Act as donors in dative covalent bonds (e.g. chelation therapy)
- Act as acceptors for biological donors
What is D-penicillin amine used for?
Treatment of copper and arsenic poisoning
What is Dimercaprol used for?
Treatment of mercury, lead and arsenic poisoning
What is Desferoxamine used for?
Treatment of iron overdose
What is Cis-platin used for?
Anti-cancer agent