What is electronegativity?
The ability of an atom in a molecule to attract electrons to itself
Explain the trends in the periodicity of alkali metals?
the atomic radius and the ionic radius increase down the group
the electronegativity and ionisation energy decreases down the group
What is the source/occurrence of alkali metals?
- Salts - not in elemental states
Rb, Li, Cs have small natural abundance
How does Extraction take place?
Electrolysis starting from NaCl (KCl, LiCl)
what is the characteristics of lithium metals
very reactive
soft
storage under oil or oxygen free atmosphere
alkali oxide: - heating in excess of air
alkali chloride:- prepared by reacting metals with cl2 and good aqueous solubility
alkali carbonate - li2co3 sparingly soluable
uses of lithium?
- Industrial use: batteries, glass manufacture, metal alloys
Clinical use: manic depression and bipolar disorder
What is a diagonal relationship?
Adjacent elements of the second and third periods have similar properties
mg2+ and li
have similar ionic radius - competition for binding sites in protein
have similar solubility
hydrated compounds
what is the clinical use of lithium
- Orally taken as Li2CO3
- Max dose per day 30mmol
- Can be irritating to GI tract
- Treatment is monitored 12h after
- Very narrow therapeutic index
- Magnesium balance in blood and urine is altered
- Lithium is not soluble in lipids and therefore does not pass plasma membrane
- Exchange into cells by
○ Lithium sodium counter transport
○ Anion exchange
○ Unrelated transport molecules
Where is lithium distributed in the body?
- Uniformly in body tissues, blood plasma with external cell
Mostly distributed to bone and kidney
Why does bones have the highest concentration of lithium?
Bones act as sink for lithium
Body try’s to get rid of it by storing it safely
Why is lithium used as a mood stabiliser?
They work by inhibiting key enzyme in bipolar disorder - active site for carbamazepine
Li is very toxic - narrow therapeutic window
what are some adverse effects caused by lithium?
- tremor
weight gain
-memory problems
-extreme doses can cause dirahoea and nausea
diabetes inspidus
decreased thyroid levels
kidney functions has to be closely measured
What is the interaction with lithium and NSAID?
- 60% increase in blood lithium concentration
- This is because
○ It causes reduced clearance of lithium through kidney - lithium poisoning possible
Sodium depletion make lithium toxicity worse, therefore concurrent use of diuretics is hazardous
- This is because
What are some lithium drugs on the market?
camcolit
liskonum
praidel
lithium citrate
